Easy Milk Chocolate Frosting

3 tablespoons margarine
2 tablespoons cocoa
1 1/2 cups powdered sugar
2 tablespoons milk
1 teaspoon vanilla Melt 3 tablespoons margarine over low heat in a saucepan. Remove from heat and add 2 tablespoons cocoa, stir until dissolved. Add 1 1/2 cups powdered sugar, 2 tablespoons milk, and 1 teaspoon vanilla. Beat until smooth. For plain frosting, add 2 more tablespoons powdered sugar instead of the cocoa.