Combine egg whites and powdered sugar in a heavy duty mixing bowl with whisk attachment.
Whisk on low to combine. Once combined, turn mixer to high and whisk for 5-10 minutes until stiff peaks have formed.
Turn mixer off and switch from whisk to a paddle attachment.
With mixer on low speed, begin adding butter a few pieces at a time until all butter has been added.
Mix on medium low until buttercream is creamy, about 5-10 minutes.
Add extract of your choice and beat on low until incorporated.
Have ingredients at room temperature.
After adding butter, the mixture will break, or look soupy. Walk away and let the mixer do its job.
Store at room temp for 3 days, refrigerate for 2 weeks, freezer for 3 months. Bring cold/frozen buttercream to room temperature and beat on low with paddle before using.
Don’t skimp on the flavoring! This recipe will taste like whipped butter if you don’t add enough flavoring. Liquors work great too!
Pasteurized egg whites can be found in a carton in the egg department of most grocery stores. Be sure to select a carton of egg whites only!
Fresh egg whites are not suitable for this recipe because they have not been exposed to heat in order to destroy potential bacteria.
If the buttercream has a lot of air bubbles, microwave it in 10 second intervals until you see a small amount of melted butter around the top rim of the bowl. Return to mixer and using the paddle attachment, beat on low. This will return the buttercream to a smooth and creamy state.