A simple "scratch" chocolate buttercream frosting made from just 6 basic ingredients you probably have on hand
Combine powdered sugar, cocoa and salt. Add milk and vanilla. Blend until smooth. Add butter and beat until of spreading consistency. Add a little more powdered sugar or milk if needed. Scrape down bowl a time or two.
This makes enough for a 13" x 9" cake, 2 layers of a 9" round or 12 cupcakes.
Hint: make sure cake is well cooled before frosting.