1/2 c. butter
1 c. brown sugar, packed
1/4 c. milk
1 3/4 to 2 c. powdered sugar

Melt butter in pan and add brown sugar, boil over low heat for 2 minutes stirring. Stir in milk, bring to boil, stirring constantly. Cool to lukewarm, gradually add powdered sugar. Beat until thick enough to spread. Add a little hot water if too thick.