1/2 c. butter
1/2 c. baking cocoa (powdered)
1/3 c. milk
3 2/3 c. confectioners' sugar (1 lb.)
1 tsp. vanilla

Microwave butter in glass bowl on high until melted, about 1 minute. Stir in cocoa until smooth; microwave on high until mixture boils, 1/2 to 1 minute. Add milk and confectioners' sugar. Beat to spreading consistency; blend in vanilla. Spread while warm.

Makes about 2 cups frosting, enough for 1 cake.