This is my go to peanut butter buttercream recipe! It’s really just adding some peanut butter to my classic american buttercream, but the peanut butter really thickens the frosting! I add a touch more heavy cream and a tiny bit of egg whites to thin it out, and make it nice and smooth.
Beat the butter and peanut butter on a medium speed for 30 seconds with a paddle attachment, until smooth.
Slowly add in the powdered sugar, 1 cup at a time. Alternate with small splashes of cream.
Once fully mixed, add in the egg whites and salt, and beat on low until the ingredients are fully incorporated, and the desired consistency is reached.
If the frosting is too thick, add in additional cream (1 teaspoon at a time). If the frosting is too thin, add in more powdered sugar (quarter of a cup at a time).
If you are making frosting for a cake, it is important to mix the buttercream on low at the end of the process for a couple minutes, to get out any extra air that might have be incorporated during the mixing process. This will make it easier to get super smooth sides on your cake!