a base, this can be either prepared pudding, custard or even just powdered sugar
flavorings, optional
Instructions
In a stand mixer fitted with the whisk or paddle, or in a mixing bowl if using a handheld mixer, beat the butter until smooth and fluffy and lightened in color, about 2 minutes.
Add the base one tablespoon at a time, mixing well after each addition.
Add flavorings and beat until buttercream looks thick, smooth, and creamy, about 3 minutes.
Recipe by The Tough Cookie at https://thetoughcookie.com/2015/01/12/make-buttercream-beaten-butter-method-battle-buttercreams-2-0/