Recipe(tried): Wacky Cake Variation and Penuche Icing

My Mom's recipe for Wacky Cake was the same as the one posted except she used 1/3 cup oil in place of the melted butter/margarine. She would sometimes double the recipe and always frosted it with the following frosting:

Penuche Icing

1/2 cup margarine
1 cup packed brown sugar
1/4 cup milk
1 3/4 to 2 cups powdered sugar

Melt margarine with brown sugar, boil over low heat for two minutes stirring constantly. Add milk and boil again.Remove from heat and gradually beat in powdered sugar.

Makes enough for a 13 x 9 cake.