1 c. brown sugar
1/2 c. granulated sugar
1/2 c. milk
2 tbsp. butter
1/2 tsp. vanilla
1/8 tsp. salt

Mix all ingredients together and cook over medium heat until drops of icing will form soft ball when dropped into cup of cold water, 238 degrees. Remove from heat and beat until icing reaches spreading consistency, about 15 minutes. For a large cake, double recipe.