Silky smooth vegan Swiss meringue buttercream with a kick of espresso. This vegan coffee buttercream is completely eggless and dairy-free and made with brown sugar! Perfect for frosting vegan cakes and cupcakes.
Mix together the instant coffee and boiling water and set aside to cool.
Add the aquafaba and sugar to a large bowl and place the bowl on top of a saucepan with a few inches of water in the bottom - this is known as a bain-marie (water bath). Bring the temperature up to medium and allow the mixture to heat for a few minutes until the sugar is dissolved.
Remove the bowl from the heat and use an electric whisk (or transfer the syrup into your stand mixer) and beat on high speed for 15-20 minutes until the mixture is completely cooled and glossy. The mixture should be stiff and glossy and should stay in the bowl if you turn it upside down (carefully!).
Start slowly adding the chunks of butter to the meringue, one at a time, allowing the mixture to incorporate for about 5 seconds between each one. The mixture will flatten as you add the butter, just continue to add the butter as it will stiffen when the full amount of butter is incorporated.
Once all the butter has been added the mixture be thick like buttercream, continue to whisk on low for 5-10 minutes until the mixture is fluffy and lightened in color. If the mixture looks split, don't worry it will come together with enough blending.
Lastly, add the cooled coffee mixture to the buttercream and continue to whisk for a couple of minutes until combined.
Storage
You can store this coffee buttercream in an airtight container in the fridge. It will harden when chilled, so before use, allow it to come to room temperature until it comes back to a creamy consistency.
Notes
Aquafaba: The liquid part from tinned chickpeas.
Vegan butter: I use flora plant butter, I have not tried Earth Balance, therefore, cannot personally recommend it.
Room temperature butter should be firm to the touch, not soft. If you live in a warmer environment then take the butter out of the fridge 15-20 minutes before using.
Plain vegan Swiss meringue buttercream: You can skip the coffee flavoring and keep this buttercream plain. I recommend adding a half teaspoon of vanilla instead to give a vanilla flavor.
White sugar: You can use caster sugar (superfine) instead of soft brown sugar for this recipe.
Sometimes in warmer, more humid environments it can take a bit longer to whip the mixture to stiff peaks. Place the mixture in the fridge for an hour and then whisk it again, it should come together with some patience!
Generally, this can happen if the butter you used was too soft. The vegan butter should be room temperature and firm to the touch (not soft!).
If your buttercream appears to be split once all of the butter has been whipped in, continue adding some chilled vegan butter in small amounts and the mixture should emulsify.