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

Cook the first five ingredients together over medium heat until thick. Remove from heat, and cool a little. Add powdered sugar and beat until smooth. Spread over a 9"x13" cake. It's a thick frosting that's good over bars.