This frosting is so good on apple cake but my Grandma Lillie (Jeanette Lillie, my Dad's mom) always put it on her banana cakes. She made the best banana cake ever! I can't find the recipe for the cake, but here is the frosting recipe.
11. Melt together the brown sugar and the butter in a saucepan. Add salt and milk. Add the powdered sugar a little at a time because you might not need all of it to get to a frosting thickness. Also, if you use less it makes a great icing.