1/2 c. butter
1 c. brown sugar
pinch of salt
4 tbsp. milk
2 c. powdered sugar
1/2 tsp. vanilla

Melt butter. Stir in firmly packed brown sugar and a pinch of salt. Cook over low heat, stirring constantly, for 2 minutes. Add milk. Stir constantly until mixture comes to a boil. Remove from heat. Stir in gradually sifted powdered sugar. Add vanilla and mix well. If too thick, add more milk.