Quick Caramel Frosting
Makes enough for 9- by 13-inch pan, with leftovers.
This is adapted slightly from "The All New Fannie Farmer Boston Cooking School Cookbook."
1/2 c. (1 stick) butter
1/2 c. brown sugar
1/4 c. milk
About 2 c. powdered sugar, or more
1 tsp. vanilla