It was just so buttery and so chocolaty , and so good! This is birthday cake frosting, plain and simple, terrific on Mom's Layer Cake, or just on the tip of your finger!
Place the butter and cocoa powder in a large mixing bowl. Blend with an electric mixer on low speed until the mixture is soft and well combined, 30 seconds. Stop the machine. Place the confectioners' sugar, 1/3 cup milk, vanilla and salt in the bowl, and beat with the mixer on low speed until the frosting lightens and is fluffy, 2 to 3 minutes. Add more milk if the frosting is too thick or confectioners' sugar, 1 tablespoon at a time, if the frosting is too thin.
Use the frosting to frost the cake or cupcakes of your choice.