This Carmel Icing goes perfectly with Chocolate Cake and stays soft if you make it according to these directions. The secret is to just bring to a boil, remove from heat and let it cool off before adding your powdered sugar. You will end up using a lot less powdered sugar that way.
1 stick butter
1 cup light brown sugar
1/4 cup milk
1/2 teaspoon vanilla
Melt butter and sugar over medium to low heat for 2 minutes stirring constantly. Start timing when butter starts melting. After 2 minutes, add 1/4 cup milk. Just bring to a boil then take off of heat and set pan in cold water till lukewarm.
Add vanilla and powdered sugar to desired consistency.