1 1/2 c. sugar
1 c. evaporated milk and milk
5 sq. unsweetened baking chocolate
1/2 c. butter
1 tsp. vanilla

Combine sugar and milk in heavy saucepan; bring to boil, stirring constantly. Reduce heat and simmer 6 minutes without stirring. Remove from heat; add chocolate. Stir to blend. Stir in butter and vanilla. Chill until mixture begins to thicken. Beat until thick and frost.