enough for one 13- x 9- inch cake
2 cups sugar
1/2 cup cocoa
1/2 cup milk
1/2 cup plus 2 tablespoons butter or margarine, softened
2 tablespoons light corn syrup
1 teaspoon vanilla extract
Combine all ingredients, except vanilla, in a heavy saucepan; bring to a boil, and cook 1 minute, stirring constantly. Remove from heat, and stir in vanilla. Cool slightly. Beat until spreading consistency. Spread immediately over cooled cake.