1 cup confectioners’ sugar
1/2 cup packed brown sugar
2 tablespoons butter
3 tablespoons milk
1/2 teaspoon vanilla extract
In a medium saucepan, melt the butter then add the milk and brown sugar. Bring to a boil and continue to boil for 1 minute. Remove from heat, and whisk in 1/2 cup confectioners’ sugar. Cool slightly, then very vigorously* whisk in the remaining 1/2 cup confectioners’ sugar. Frost cakes while the frosting is still slightly warm.
*if you have problems doing this by hand, use an electric mixer, it is very important to whisk very quickly or it will not be smooth.
This is not a fluffy icing, but it is a thick and tasty one. It’s hard to get a good carmel flavor in an icing, but I think I did it.