Makes enough to frost 12 cupcakes(double the recipe for 8-inch cake)
Beat the confectioners’ sugar, butter, and cocoa together in a freestanding electric mixer with a paddle attachment on medium-slow speed until the mixture comes together and is well mixed. Turn the mixer down to a slower speed. Add the milk to the butter mixture a couple of teaspoons at a time. Once all the milk has been incorporated, turn the mixer up to high speed. Continue beating until the frosting is light and fluffy, about 5 minutes. The longer the frosting is beaten, the fluffier and lighter it becomes.