1/2 c. butter
1 c. packed brown sugar
1/4 c. milk
2 c. confectioner's sugar

Melt butter in saucepan; add brown sugar. Boil over low heat for 2 minutes, stirring constantly. Stir in milk; boil, stirring constantly. Cool to lukewarm. Gradually add confectioner's sugar. Beat until thick enough to spread. If too stiff, add a little hot water.