4 1/2 c. powdered sugar
2/3 c. unsweetened cocoa
1/2 c. butter
1/2 c. milk
2 tsp. vanilla

Combine sugar and cocoa. Cream butter and 2 cups of cocoa mixture in small mixer bowl. Add remaining cocoa mixture alternately with milk, heating until of spreading consistency. (An additional bit of milk may be needed.) Blend in vanilla. Fills and frosts 3 (8 or 9-inch) layers.