Chocolate Frosting Mississippi Mud Cake
["1 lb. box powdered sugar", "1/4 c. margarine", "1/2 c. milk", "1/3 c. cocoa"]
["Combine all ingredients in a small mixing bowl.", "Mix well. Spread frosting over marshmallows.", "Layer on warm cake."]
["powdered sugar", "margarine", "milk", "cocoa"]