Caramel Frosting

My grandma on my mom's side is known in our family for making a yellow cake (from a box) with caramel frosting that is REALLY, really good, especially with some quality vanilla ice cream on the side.  Here's the recipe for the frosting:

-1/2 stick butter or margarine
-1/2 cup dark brown sugar
-3 Tablespoons milk
-3 oz. plain cream cheese (whipped works fine)
-3 cups powdered sugar

-Melt the butter in a small saucepan and stir in the brown sugar.  Boil for 2 minutes, stirring constantly.  Remove from heat and stir in the milk.  Put the pan back on the heat and boil for another minute, then cool.

-Using a hand mixer, beat the cream cheese with 2 cups of the powdered sugar and add the cooled caramel sauce.  Add the other cup of powdered sugar and beat until smooth.

I made yellow cupcakes when I hosted a book club this week.  To make them easy to eat, I carved a small portion out of the middle of each one with a paring knife, then filled the hole with the frosting and made a plop on the top. (I put the frosting in a ziploc bag and cut the corner off to do this).  They turned out great!