1. Combine margarine and brown sugar in a saucepan.
2. Heat to boiling, stirring constantly.
3.
Boil and stir over low heat for 2 minutes.
4. Add milk.
5. Stir to blend well and bring to a boil again.
6. Cool to lukewarm.
7. Gradually stir in powdered sugar.
8. Beat until smooth.
Frosts one 8 or 9-inch 2-layer cake or one 9" x 13" pan cake.
