1 1/2 c. packed light brown sugar
6 tbsp. butter
9 tbsp. evaporated milk
1 1/2 tsp. vanilla extract
2 1/2 c. sifted confectioners' sugar

Stir brown sugar, butter, and milk over medium heat. Cook only 1 minute. After it begins to boil, remove from heat. Add vanilla and confectioners' sugar. Stir until spreadable.