A common issue with most buttercreams is their overly buttery taste and texture. To address this, I've introduced a pre-conditioning technique called making "Frosting Butter." This method aerates the butter and enhances it with just the right balance of sweetness and flavor, paving the way for optimal creamy consistency and smooth emulsification. The result is a silky, well-balanced buttercream that isn't dominated by butteriness. Moreover, Frosting Butter ensures a stable emulsion that resists curdling or separation, even after refrigeration or freezing.

How does Frosting Butter Work: The Science Behind it all

I developed this technique while studying and rewriting my Swiss Meringue Buttercream recipe. So, to explain how and why frosting butter works, we’ll have to back up a bit and talk about Swiss Meringue Buttercream, which is traditionally made by whipping up a cooked egg white sugar mixture until fluffy and adding butter. Specifically, I wanted to study meringues and their purpose in buttercreams.

Exploring this topic led to a pivotal experiment that inspired the creation of Frosting Butter, which I now incorporate into nearly all my buttercream recipes.

What is a meringue, and what role does it play in buttercreams?

A meringue is a light, airy, sweetened mixture made by whipping egg whites with sugar. It's called foam when air bubbles are evenly distributed within a liquid (or solid) mixture. We often see recipes with meringues, usually described as soft, medium, or stiff. This texture describes how fluffy or airy the meringue is. It highly depends on factors such as whipping intensity/duration, type of eggs, type of heating preparation, and other ingredients in the mixture, like sugar.  

Meringues are foams whose lightness hinges on the amount of air incorporated into the egg whites. This is possible due to specific proteins in the egg whites. Picture these proteins as balled-up pieces of string. When you whip the egg whites, these "strings" unravel and interlock, forming a complex net that efficiently traps air, creating volume and airiness. As whipping continues, this net strengthens, developing more connections and increasing the meringue's airy texture.

When added to buttercreams, meringues contribute to flavor, sweetness, bulk, stability, and a lighter texture. Given their foam-like nature, I was curious about the extent to which they influence the overall air content or aeration of the mixture. 

To test this, I measured the air content of Swiss meringue buttercreams using a combination of the following preparations:

Unwhipped (non-aerated) Butter: Softened butter (approximately 65 °F/ 18 °C) is cut into 1-inch chunks.
Whipped (aerated) Butter: Softened butter (approximately 65 °F/ 18 °C) is whipped at high speed with the whisk attachment until it is lighter in color and texture, about 2-3 minutes.
Syrup (non-aerated) Meringue:  Fresh egg whites and sugar are heated over a bain marie until 160 °F/ 71 ° C, and the thick, viscous syrup is cooled.
Whipped (aerated) Meringue: Fresh egg whites and sugar are heated over a bain marie until 160 °F/ 71 ° C and whipped for 10 minutes until cooled and stiff with glossy peaks.

Notably, the combination of whipped butter and whipped meringue resulted in the highest air content in the buttercream. However, an intriguing discovery was that the aeration levels were nearly identical across all four test combinations, regardless of whether the butter or meringue was whipped.

Key takeaways from this experiment include:

• Whipping the meringue doesn’t significantly increase the air content in the final buttercream.
• Whipping the butter contributes slightly more to aeration.

Why I like Frosting Butter (more than a Whipped Meringue for a Buttercream)

Making Frosting Butter offers significant benefits, enhancing buttercream's texture and flavor. By incorporating a small amount of powdered sugar, this technique aerates the butter, initiates the emulsion process, and sweetens the butter. This pre-conditioning step produces butter with the ideal creamy texture and temperature for crafting a perfect buttercream emulsion, yielding a less buttery and more aerated final product. Additionally, the stability of this emulsion makes buttercreams made with Frosting Butter much easier to re-whip after being stored cold.

While you might compare this process to making American Buttercream, which primarily involves butter and powdered sugar, the key difference lies in the ratios. Frosting Butter is carefully calibrated so that the sugar content is just enough to slightly aerate the butterfat before dissolving into the water in the butter, avoiding any graininess. This method is distinct from American Buttercream, which does not involve emulsification.

The effects of Frosting Butter are so beneficial that I use it across all my high-butter content True Buttercreams, not just meringue-based ones. The only exception is Ermine Buttercream, which doesn't show significant changes due to its lower butter content.

How to make Frosting Butter:

For proper aeration, ensure the butter temperature is around 60-70 °F (15-21 °C) (1a). 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 (1a, inset).

Butter must be at a workable temperature to allow the whisk to move about the butterfat and push air between the fat. Different fats have varying temperatures at which this can occur, but for butterfats (also referred to as “milkfats”), this is around 60-70 °F (15-21 °C). Too low of a temperature and the fat is too solid; too high of a temperature, the fats melt into a liquid state (aka “oil”) and cannot create stable pockets that hold air.

Add the butter to your mixing bowl and whisk on high speed for about 3-5 minutes, scraping down the sides at least once (1b,c). Aerated butter will still be paler, more voluminous, and ball up inside the whisk (1d).

Using a whisk is an efficient way to push air into the butter. A paddle attachment will work, too, but it will take more time to get the same volume. 

Add powdered sugar, vanilla extract, and a small pinch of salt (1e, f). These are just the initial amounts, so don’t worry about the final flavor now, as you can add more at the very end. 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 (1g).

Powdered sugar is great for Frosting Butter because the granules are so small that they can help a bit with aeration and dissolve easily when they hit the water containing the butter. The sugar, along with a bit of vanilla extract and salt, adds to the water-in-oil emulsion that makes up butter, giving it a sweetness and flavor that will permeate every bite of this buttercream. Fats take up flavor very well, so it helps to add the vanilla and salt at this phase. In a sense, we are making a mini-emulsion before moving on to the more significant emulsification step with the other water-based component of the buttercream (e.g., meringue, condensed milk, pastry cream, etc.)

Pre-conditioning the butter with sugar causes it to become lighter in color; compare the difference in appearance before whisking on the left versus after on the right (1e). If you taste it, Frosting will be lightly sweetened and nicely flavored with salt and vanilla. 

The Frosting Butter is now ready for further emulsification steps. It’s at the right temperature and texture, but you can store it for use later. Just follow my Frosting Storage Guide and allow the Frosting Butter to come to room temperature before using it. 

Frosting Butter is used in almost all of my True Buttercream recipes (except for Ermine Buttercream, which uses such a low ratio of butter that it’s unnecessary). You can check out this Buttercream guide to view the True Buttercreams in one place.