Creamy, Luxurious French Buttercream: Your Complete Guide

Yield
1 or 3 cups
Prep time
20-30 mins
Cook time
5-15 mins
Total time
25-45 mins + cooling

French buttercream is a luxuriously decadent frosting made primarily from eggs, sugar, and butter. Flavor-wise, it’s a bit more complex than the meringue buttercreams because the added yolks impart a rich, creamy, pastry cream-like flavor. The silky smooth texture makes it perfect for all your cake decorating needs. My method uses a simple water bath, making this frosting ideal for those looking to elevate their frosting game in terms of decorating, flavor, and texture. 

Welcome to my ultimate French Buttercream guide! 

We'll explore texture, aeration, and ingredient chemistry and learn how this frosting differs. Learn if it's suitable for your dessert and get the exact process to understand and customize your perfect frosting.

What is French Buttercream?

My French Buttercream is a type of True Buttercream, a large family of butter-based frostings made by creating stable emulsions. 

French Buttercreams fall under the True Buttercream Family, part of the larger Emulsions category. Frostings within the same group share similar characteristics, making it easy to navigate the world of frostings. 

True Buttercreams are a family of stable emulsion frostings, where fat and water-based ingredients are mixed to create a thick, creamy texture. I’ll often also refer to these as “emulsion-based buttercreams.”

Generally, True Buttercreams: 

  • moderate sweetness, 
  • low aeration, 
  • a creamy and buttery texture, 
  • the ability to create intricate piped designs and smooth cake sides, 
  • excellent stability at room temperature and under pressure, and 
  • are easily dyed and flavored. 

So, what sets French Buttercream apart from other Frostings? 

Let’s get into the specifics of French buttercream:

French is a typical buttercream used in classic pastry and desserts. Because of the cooking step, this one is ranked as an intermediate recipe as it takes a bit longer than my beginner recipes. It is on the lower end of that spectrum, so I encourage you to try it if you’re starting with my True Buttercreams. 

What is the texture of French Buttercream?

My French buttercream is creamy, silky-smooth, and has a melt-in-your-mouth texture. This is achieved through emulsification, which evenly distributes the egg-based sugar syrup throughout the butterfat, reducing the buttery flavor and texture. With a fat content of 40%, this buttercream has one of the highest fat levels among my European buttercreams, contributing to its creamy texture.

I measure the aeration of my frostings, which is the percentage of volume occupied by air. Generally, my European buttercreams have low aeration, with French buttercream at around 11%. This means that for any given volume of frosting, 11% is air, while the rest comprises ingredients like butter, sugar, and water. For comparison, a highly aerated frosting like whipped cream can have up to 50% air.

Aeration is crucial in understanding texture, affecting mouthfeel, greasiness, and spreadability. Although most of my emulsion-based frostings have low aeration, don’t let that deter you. Air isn’t the only factor influencing texture. In emulsion-based frostings, the high ratio of silky or creamy syrups interlaced with butterfat creates the luxurious, melt-in-your-mouth creaminess of the final buttercream.

What is the taste and flavor of French Buttercream?

The overall flavor of this buttercream is a lighter version of a sweet and vanilla-scented pastry cream. The egg yolks contain many fats, which pass on some lovely flavors. And don’t worry about it tasting “eggy” - that’s not how I would describe the flavor. You taste more of the sugar and butter, and it’s finished with a slight custardy flavor at the end.

What ingredients are needed for French Buttercream?

(Please note that ingredient amounts may look different here and in the step-by-step tutorial photos. Although I might be demonstrating a different final yield here, the method remains the same regardless of your quantity. Always follow the amounts specified in the recipe card.)
1 | WHOLE EGGS (OR EGG YOLKS ONLY)

Eggs add flavor, color, and moisture. I use whole eggs in my base recipe, but you may have seen that most French buttercream recipes use just yolks. You can do that with this buttercream as well, and I’ll note the conversion of whole eggs to yolks in the section below, as well as the recipe card.

The final color of your buttercream will be highly dependent on the color of your yolks, so if you prefer a lighter yellow frosting, look for a paler yellow rather than a vivid orange. Typically, pasture-raised hens that feed on carotenoid-rich plants yield oranger yolks.

2 | WHITE GRANULATED SUGAR

Sugar will dissolve into the water contained in the eggs and contribute to this buttercream’s delicious sweet taste.

3 | UNSALTED BUTTER

Butter is the base fat for this buttercream. It is vital to any of my emulsion-based frostings because it contains a component inside the butter called an emulsifier. This ties together ingredients; in this case, it’s bringing together the egg syrup and fat in the butter.

I always use unsalted butter in all my frostings because that allows you to customize the salty flavor at the end. Not all salted kinds of butter contain the same salt, so that the frosting may become too salty.

4 | POWDERED SUGAR

You may wonder why we use two types of sugar in this recipe, but the powdered sugar serves a different purpose. It not only helps sweeten the overall buttercream but, mixed directly with the butter in a separate step, will help flavor and slightly aerate (or “cream”) the butterfat, which gives the final frosting a dreamy, creamy texture. 

5 | VANILLA EXTRACT

Vanilla extract is a general flavor enhancer for baked goods, and here, it is the primary flavoring element for this frosting. Extracts are generally interchangeable to make easy flavor modifications, but be sure to google it. (For instance, almond extract is potent, and you’d likely want to start with 25% of the amount of vanilla.) Also, vanilla bean paste is lovely here as it adds little vanilla bean specks throughout the frosting.

Natural vanilla extract tends to be dark brown, making the final frosting a bit cream-colored, so if you’re trying to minimize this, consider a clear vanilla extract. These extracts are artificially flavored, but I like them in cakes and frostings. 

6 | FINELY GRANULATED SALT

A pinch of salt enhances the flavor and balances the overall sweetness of this frosting. I typically use flaky kosher salt in my baking, but crispy salt bits are not appealing in frostings, so I exclusively use finely granulated salt. This allows the salt to dissolve more readily.

What effect do egg yolks have on buttercream, and how can you substitute whole eggs for just yolks in French Buttercream?

The most apparent contribution egg yolks make to a buttercream is the color. The final buttercream color ranges from light to medium yellow, which depends on your egg yolks' vibrancy. 

Egg yolks also significantly contribute to flavor and texture. If you've ever wondered why egg yolks are so delicious in carbonara pasta or floating in a bowl of ramen, it's because of the combination of fats and glutamic acid. The fats provide a creamy, rich flavor and texture, while the glutamic acid adds a savory umami note.  Umami is particularly special in desserts since it's less common than other tastes. I can spot the flavor of egg yolks in buttercream from a mile away; they add a depth of flavor that is utterly delicious.

Below, you’ll find the chemical makeup contained within a chicken egg: 

In baking, it's helpful to understand each component's fat, protein, and water content. For example, egg yolks contain almost half the amount of water and nearly 50% more protein than egg whites, and they have significantly more fat than the almost fat-free whites. (Note that using equal amounts is important when comparing these components. You may have read that egg whites contain the bulk of the egg's protein, but that's only because there is more white than yolk in a single egg.)

So, what exactly happens when you substitute whole eggs with egg yolks in a buttercream, and how do you do it?

In French Buttercream, substitute two egg yolks plus two teaspoons of water for every large whole egg. 

The graphic above shows that the yolks-only Frech Buttercream is slightly more yellow. I typically make French buttercream using whole eggs. It’s cheaper and more efficient, and it gets me 90% of the way there flavor- and texture-wise when I want a French buttercream. When leftover yolks from another recipe (macarons or meringues), I will go for the yolks-only version.

Step by step:

How do you make French Buttercream?

You may have seen French Buttercream methods that use sugar syrup (similar to the technique for Italian Meringue Buttercream), but after seeing Stella Parks prepare hers over a water bath, I knew this was an excellent modification. This method is more accessible and safer, reliably bringing the raw egg mixture to a sufficiently high temperature.

STEP 1 | SET UP THE DOUBLE BOILER (BAIN-MARIE).

WHY:

Heating over a double boiler reduces the risk of overheating or heating a mixture too quickly. This method is commonly used for delicate preparations sensitive to temperature changes, such as chocolate, custards, and meringues. It prevents direct contact with high heat, allowing the temperature to rise gently and gradually.

HOW:

Find a pot that allows a large bowl to sit on top. You don’t want to create a tight seal, as steam needs to escape. Here, I’m using a bit of foil, which allows for a slight gap for steam release (1a). Fill the pot with water so it’s within an inch of the bottom of your bowl, but don’t allow it to sit in the water (1b).

Some bakers mention that it takes forever to heat the mixture, possibly due to a couple of factors. The temperature is highest at the water's surface, so there might be too much of a gap between the bottom of the bowl and the water. Also, try using a metal bowl, which conducts heat more quickly and efficiently than glass. I'm using glass here for visibility, but I'll switch to my metal bowl for the rest of the recipe.

STEP 2 | PREPARE AND HEAT THE EGG SYRUP (AND OPTIONALLY, WHIP).

WHY:

The egg syrup mixes whole eggs (or the yolk-water substitution) with white granulated sugar. Mixing immediately when the sugar touches the yolks is essential because white sugar is highly hygroscopic, meaning it quickly absorbs water from its surroundings. Since egg yolks have a high fat and protein content with relatively little water, leaving sugar on them too long will draw out the little moisture it has and cause the yolks to dry out, leading to specks in your final buttercream.

You'll need a thermometer to heat this mixture to at least 160°F (71°C). This is the temperature required to kill potentially pathogenic strains of Salmonella that may be present in raw eggs. The mixture will be runny but safe to consume after reaching this temperature.

HOW: 

Add eggs (or yolks and water for the yolk-only substitution)  to a large heat-proof mixing bowl (2a). (If you plan on whipping your egg syrup, use the bowl of your stand mixer.) Add the sugar (2b) and immediately start mixing with a spatula until the sugar is evenly distributed (2c,d).

Place the bowl on top once your double boiler is at a gentle simmer. Use a spatula to gently stir periodically (2e) and heat until the egg syrup reaches 160°F (71°C) (2f). Then, pour the hot syrup into a heat-proof bowl or measuring cup (2g).

Optionally, you can whip the egg syrup to create a runny foam after it reaches the desired temperature, though it makes little difference in the final buttercream texture. The foaming effect is even less pronounced in this recipe than in a standard meringue made with just egg whites because the high-fat content in egg yolks interferes with the proteins’ ability to hold large air pockets. (I discuss this more in my Swiss Meringue Buttercream tutorial under the 'How to Bake like a Scientist' section.) However, if you want to do this, place the bowl in your stand mixer and use the whisk attachment to mix on high speed until the mixture becomes slightly more voluminous and paler. Then, pour the egg foam into a heat-proof measuring cup, as indicated above.

STEP 3 | PREPARE THE FROSTING BUTTER.

WHY:

A common complaint about true buttercreams is their overly buttery taste and texture. To address this, I've developed a pre-conditioning method that makes what I call 'Frosting Butter.' This technique aerates, pre-sweetens, and flavors the butterfat, ensuring an optimal creamy texture and temperature for emulsification—crucial for all true buttercreams. The final buttercream is such a homogenous emulsion that it’s incredibly silky smooth and doesn't have an overpowering buttery taste. Additionally, frostings made with Frosting Butter are easier to re-whip without curdling after refrigeration or freezing.

HOW:

For proper aeration, ensure the butter temperature is around 60-70 °F (15-21 °C) (3a). You don’t need a thermometer, but when the butter is at this temperature, you should be able to slide the whisk attachment into it with moderate pressure (3a, inset).

Add the butter to your mixing bowl and whisk on high speed for about 3-5 minutes, scraping down the sides at least once (3b). Aerated butter will still be paler, more voluminous, and ball up inside the whisk (3c).

Add the powdered sugar, vanilla extract, and a small pinch of salt (3d, e). Mix on high speed for another 2-3 minutes. You’ll notice that the butter is slightly glossier (that’s the sugar) but still has a good fluffy, voluminous texture that balls inside the whisk (3f).

STEP 4 | COMBINE THE COOLED MERINGUE SYRUP WITH BUTTER.

WHY:

Adding the meringue syrup in increments lets the butter emulsify gradually, producing a smooth and shiny buttercream.

HOW:

Ensure that your egg syrup (or foam) is at room temperature, and add in 2 to 3 additions (4a), whipping for about 1 minute after every addition. Once all the egg syrup has been added, mix for an additional minute on high speed (4b).

‍STEP 5 | SMOOTH AND ADJUST FOR FLAVORINGS.

WHY: 

With its multiple wires, the whisk is much more efficient at emulsifying than a paddle with a single thick wire. However, using the whisk attachment also incorporates a lot of air, which can form large air pockets. To minimize this, switch to a paddle attachment (preferably with a silicone edge) during the final mixing. This will smooth the frosting against the bowl and significantly reduce significant air gaps in your final frosting. 

HOW:

Switch over to the paddle attachment and smooth it at the lowest speed for a few minutes. Taste the buttercream and adjust for salt and vanilla. The final buttercream will be silky smooth with a melt-in-your-mouth texture, ready to frost your cakes (5a,b).

Storage Tips

Leftover buttercream stores well in the fridge or freezer. Additionally, this buttercream can be made ahead of time for larger cake projects.

For a detailed tutorial, check out my How to Store Buttercream Guide.

Video

Read this before you begin

Measure by weight, if possible.

Measuring by weight is the best way for you to replicate my recipes. I develop recipes using ingredients (even liquids) measured in grams, which is why you see them listed first in the recipe cards. For measurements under 5 grams, I will typically only list the volumetric measurements (teaspoons, etc.), as most home scales are not precise for such small weights.

In most cases, I have converted grams to volumetric measurements (aka US customary units) for bakers who prefer this method. However, the measurements are not as precise and may have awkward proportions. The recipes should still work, but for the ultimate precision, try to use weight.

This is the OXO scale I use daily. I also purchased this budget version of a good scale, which I keep at my Mom’s house for baking. If you’re interested in other tools I use for my baking, I’ve compiled a list here.

Use room temperature ingredients.

All my ingredients should be used at room temperature, or 65-75 °F/18-24 °C. I will always indicate if you need something outside this range. If no details are given, room temperature is the default. 

Pay attention to the ingredient descriptions.

I try not to be brand-specific, but I will always note an interesting result from a type of ingredient, be it negative or positive. 

A specific note regarding salt: I use Diamond Crystal Kosher salt for everything on this site except for frostings. In frostings, you want the salt to dissolve more easily, and kosher salt tends to leave granules behind. If you substitute table salt (more finely granulated) for recipes that list kosher salt, you must use half the volume indicated in my recipes.

Substitutions are hard.

That’s not to say they’re impossible, though. For instance, in many cases, substituting reduced fat for whole milk (and thus reducing fat by less than 2%) will probably be fine. Using applesauce for oil or even Greek yogurt when sour cream is listed will definitely alter the fat content and adversely affect the crumb texture and density of the cake.

I experiment for hours to get these recipes to work for us. First, try to make them as written or use one of my tested substitutions, which I often dedicate a section to. Then, if necessary, you can make modifications afterward. Even then I would be pretty cautious, as substitutions are one of the hardest things to investigate in recipe development.

Read all the recipe instructions before beginning.

I’m in the “Pre-read the Chapter before Class Lecture” club... and I invite you to join! Baking new recipes can be intimidating, so let’s set you up for success. I want you to think about timeframes. Most fillings and frostings can be made ahead of time, and give you an extra day for mental space. Also, as you become a more proficient baker, you can anticipate and recognize steps. (“Oh, this has a meringue step, so I’ll need an extra clean bowl…” etc.) Ensure you go down the ingredient list and have everything at the right temperature.

Vanilla French Buttercream

Yield
1 or 3 cups
Prep time
20-30 mins
Cook time
5-15 mins
Total time
25-45 mins + cooling

Ingredients

  • 33 g (about 2 tablespoons) whole egg* (whisk the whole egg, then measure)
  • 67 g (⅓ cup) white granulated sugar
  • 100 g (7 tablespoons) unsalted butter
  • 15 g (2 tablespoons) powdered sugar, unsifted is ok
  • ½ + ⅛ teaspoon vanilla extract
  • a small pinch of fine sea salt 

For larger quantities or to pair with a cake recipe, go to my Cakeculator and choose “Vanilla French Buttercream.

  • 33 g (about 2 tablespoons) whole egg* (whisk the whole egg, then measure)
  • 67 g (⅓ cup) white granulated sugar
  • 100 g (7 tablespoons) unsalted butter
  • 15 g (2 tablespoons) powdered sugar, unsifted is ok
  • ½ + ⅛ teaspoon vanilla extract
  • a small pinch of fine sea salt 

For larger quantities or to pair with a cake recipe, go to my Cakeculator and choose “Vanilla French Buttercream.

  • 100 g (2 large) whole eggs*
  • 200 g (1 cup) white granulated sugar
  • 301 g (1 ⅓ cups) unsalted butter
  • 45 g (6 tablespoons) powdered sugar, unsifted is ok
  • 10 g (2 teaspoons) vanilla extract
  • 1/8 teaspoon salt (start with a pinch)

For larger quantities or to pair with a cake recipe, go to my Cakeculator and choose “Vanilla French Buttercream.

Instructions

  1. Set up the double boiler (bain-marie). Find a pot to hold a large metal bowl without touching the bottom. If you plan on whipping your egg whites, use the stand mixer bowl for this step. If not, use another metal bowl.

    Fill the pot with water so the bowl is directly above but not touching the water. The closer the bowl is to the surface, the better, as this is where heating will be most efficient. Remove the bowl for now and heat the water to a gentle simmer.

  2. Prepare, heat, and (optionally) whip the egg syrup.
    Add eggs (or yolks and water for the yolk-only substitution) to a large heat-proof mixing bowl. (If you plan on whipping your egg syrup, use the bowl of your stand mixer.) Add the sugar and immediately start mixing with a spatula until the sugar is evenly distributed.

    Place the bowl on top once your double boiler is at a gentle simmer. Use a spatula to gently stir periodically and heat until the egg syrup reaches 160°F (71°C). Then, pour the hot syrup into a heat-proof bowl or measuring cup.Optionally, you can whip the egg syrup to create a runny foam after it reaches the desired temperature. However, there is little difference in the final buttercream when doing this (see the step-by-step section above for an explanation). Place the bowl in your stand mixer and use the whisk attachment to mix on high speed until the mixture becomes slightly more voluminous and paler. Then, pour the egg foam into a heat-proof measuring cup, as indicated above.
  1. Prepare the frosting butter. Add the slightly softened butter to the stand mixer bowl. With the whisk attachment, mix on high speed for about 2 minutes, scraping down the sides at least once. After mixing, the butter will be lighter in color, smooth, soft, and ball inside the whisk.

    Add the powdered sugar, vanilla extract, and a small pinch of salt to the butter and whisk again at medium-high speed for another 1-2 minutes.

  2. Combine the cooled meringue syrup with the butter.
    Ensure that your egg syrup (or foam) is at room temperature and add in 2 to 3 additions, whipping for about 1 minute after every addition. Once all the egg syrup has been added, mix for an additional minute on high speed.
  3. Flavor and smooth the frosting.
    The whisk attachment introduced many air pockets, so switch over to the paddle attachment and mix on low speed for at least a few minutes to smooth out the frosting. Give the frosting a taste and adjust for vanilla and salt, if needed.

Adriana's Notes

*If you want to make the version using egg yolks instead of whole eggs, you’ll need to substitute 2 yolks and 2 teaspoons of water for every egg. For example, for the 3 cup version of frosting, instead of 2 large eggs, you will need 4 large egg yolks and 4 teaspoons of water.

  • 33 g (about 2 tablespoons) whole egg* (whisk the whole egg, then measure)
  • 67 g (⅓ cup) white granulated sugar
  • 100 g (7 tablespoons) unsalted butter
  • 15 g (2 tablespoons) powdered sugar, unsifted is ok
  • ½ + ⅛ teaspoon vanilla extract
  • a small pinch of fine sea salt 

For larger quantities or to pair with a cake recipe, go to my Cakeculator and choose “Vanilla French Buttercream.

  • 33 g (about 2 tablespoons) whole egg* (whisk the whole egg, then measure)
  • 67 g (⅓ cup) white granulated sugar
  • 100 g (7 tablespoons) unsalted butter
  • 15 g (2 tablespoons) powdered sugar, unsifted is ok
  • ½ + ⅛ teaspoon vanilla extract
  • a small pinch of fine sea salt 

For larger quantities or to pair with a cake recipe, go to my Cakeculator and choose “Vanilla French Buttercream.

  • 100 g (2 large) whole eggs*
  • 200 g (1 cup) white granulated sugar
  • 301 g (1 ⅓ cups) unsalted butter
  • 45 g (6 tablespoons) powdered sugar, unsifted is ok
  • 10 g (2 teaspoons) vanilla extract
  • 1/8 teaspoon salt (start with a pinch)

For larger quantities or to pair with a cake recipe, go to my Cakeculator and choose “Vanilla French Buttercream.

  1. Set up the double boiler (bain-marie). Find a pot to hold a large metal bowl without touching the bottom. If you plan on whipping your egg whites, use the stand mixer bowl for this step. If not, use another metal bowl.

    Fill the pot with water so the bowl is directly above but not touching the water. The closer the bowl is to the surface, the better, as this is where heating will be most efficient. Remove the bowl for now and heat the water to a gentle simmer.

  2. Prepare, heat, and (optionally) whip the egg syrup.
    Add eggs (or yolks and water for the yolk-only substitution) to a large heat-proof mixing bowl. (If you plan on whipping your egg syrup, use the bowl of your stand mixer.) Add the sugar and immediately start mixing with a spatula until the sugar is evenly distributed.

    Place the bowl on top once your double boiler is at a gentle simmer. Use a spatula to gently stir periodically and heat until the egg syrup reaches 160°F (71°C). Then, pour the hot syrup into a heat-proof bowl or measuring cup.Optionally, you can whip the egg syrup to create a runny foam after it reaches the desired temperature. However, there is little difference in the final buttercream when doing this (see the step-by-step section above for an explanation). Place the bowl in your stand mixer and use the whisk attachment to mix on high speed until the mixture becomes slightly more voluminous and paler. Then, pour the egg foam into a heat-proof measuring cup, as indicated above.
  1. Prepare the frosting butter. Add the slightly softened butter to the stand mixer bowl. With the whisk attachment, mix on high speed for about 2 minutes, scraping down the sides at least once. After mixing, the butter will be lighter in color, smooth, soft, and ball inside the whisk.

    Add the powdered sugar, vanilla extract, and a small pinch of salt to the butter and whisk again at medium-high speed for another 1-2 minutes.

  2. Combine the cooled meringue syrup with the butter.
    Ensure that your egg syrup (or foam) is at room temperature and add in 2 to 3 additions, whipping for about 1 minute after every addition. Once all the egg syrup has been added, mix for an additional minute on high speed.
  3. Flavor and smooth the frosting.
    The whisk attachment introduced many air pockets, so switch over to the paddle attachment and mix on low speed for at least a few minutes to smooth out the frosting. Give the frosting a taste and adjust for vanilla and salt, if needed.

Recipe Card - Adriana's Notes

*If you want to make the version using egg yolks instead of whole eggs, you’ll need to substitute 2 yolks and 2 teaspoons of water for every egg. For example, for the 3 cup version of frosting, instead of 2 large eggs, you will need 4 large egg yolks and 4 teaspoons of water.

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Vanilla French Buttercream

Yield
1 or 3 cups
Prep time
20-30 mins
Cook time
5-15 mins
Total time
25-45 mins + cooling

Ingredients

  • 33 g (about 2 tablespoons) whole egg* (whisk the whole egg, then measure)
  • 67 g (⅓ cup) white granulated sugar
  • 100 g (7 tablespoons) unsalted butter
  • 15 g (2 tablespoons) powdered sugar, unsifted is ok
  • ½ + ⅛ teaspoon vanilla extract
  • a small pinch of fine sea salt 

For larger quantities or to pair with a cake recipe, go to my Cakeculator and choose “Vanilla French Buttercream.

Instructions

  1. Set up the double boiler (bain-marie). Find a pot to hold a large metal bowl without touching the bottom. If you plan on whipping your egg whites, use the stand mixer bowl for this step. If not, use another metal bowl.

    Fill the pot with water so the bowl is directly above but not touching the water. The closer the bowl is to the surface, the better, as this is where heating will be most efficient. Remove the bowl for now and heat the water to a gentle simmer.

  2. Prepare, heat, and (optionally) whip the egg syrup.
    Add eggs (or yolks and water for the yolk-only substitution) to a large heat-proof mixing bowl. (If you plan on whipping your egg syrup, use the bowl of your stand mixer.) Add the sugar and immediately start mixing with a spatula until the sugar is evenly distributed.

    Place the bowl on top once your double boiler is at a gentle simmer. Use a spatula to gently stir periodically and heat until the egg syrup reaches 160°F (71°C). Then, pour the hot syrup into a heat-proof bowl or measuring cup.Optionally, you can whip the egg syrup to create a runny foam after it reaches the desired temperature. However, there is little difference in the final buttercream when doing this (see the step-by-step section above for an explanation). Place the bowl in your stand mixer and use the whisk attachment to mix on high speed until the mixture becomes slightly more voluminous and paler. Then, pour the egg foam into a heat-proof measuring cup, as indicated above.
  1. Prepare the frosting butter. Add the slightly softened butter to the stand mixer bowl. With the whisk attachment, mix on high speed for about 2 minutes, scraping down the sides at least once. After mixing, the butter will be lighter in color, smooth, soft, and ball inside the whisk.

    Add the powdered sugar, vanilla extract, and a small pinch of salt to the butter and whisk again at medium-high speed for another 1-2 minutes.

  2. Combine the cooled meringue syrup with the butter.
    Ensure that your egg syrup (or foam) is at room temperature and add in 2 to 3 additions, whipping for about 1 minute after every addition. Once all the egg syrup has been added, mix for an additional minute on high speed.
  3. Flavor and smooth the frosting.
    The whisk attachment introduced many air pockets, so switch over to the paddle attachment and mix on low speed for at least a few minutes to smooth out the frosting. Give the frosting a taste and adjust for vanilla and salt, if needed.