Note: Be sure to start with good thick/reduced aquafaba for this recipe.

In a small pot, combine together the aquafaba and sugar and bring to simmer over medium heat. Stir frequently until the sugar fully melts. Let the mixture chill overnight (or for several hours) in the refrigerator.

Note: If you are short on time, you can cool the sugar and aquafaba mixture over an icebath.

To prepare the butter and shortening, simply cut into 1-inch pieces and then place onto a plate and chill in the refrigerator or freezer until cold.

Note: This recipe can also be made with just plant-based butter but we typically use the combination of butter and shortening. If using just butter, use 285 gr (1 1/4 cups or 2 1/2 sticks)

Also, note that we have tried to make this buttercream with a variety of different kinds of butter but so far Earth Balance seems to be the most consistent.

To prepare the buttercream, place the aquafaba/sugar mixture and cream of tartar into a stand mixer. Using the balloon whisk, blend the mixture until glossy stiff peaks form—about 10 to 15 minutes. Starting on medium-low and increasing the speed to medium-high as you go.

Once stiff peaks have formed—with the mixer on medium-low, add the powdered sugar and whisk until just combined.

Next, increase the speed to medium-high and begin to add the butter, a couple of pieces at a time. Blend for a few seconds between each addition.

Whip the buttercream until it is smooth and fluffy.

Lastly, add the vanilla paste. Note: Using vanilla paste will result in a buttercream that has nice vanilla flecks throughout. If you are looking for a more clean, white look, use pure vanilla extract instead.

The buttercream can be used immediately. Note: If it’s a bit too soft, refrigerate it for a few minutes first.

If stored properly, the buttercream will keep for a couple of weeks.

This buttercream goes particularly with this Vanilla Cake, as well as a variety of other cupcake and cake recipes.