Sprinkles! Dark Chocolate Icing

When I picked up a dozen cupcakes at Sprinkles for my family, I picked out the Vanilla, Red Velvet, Dark Chocolate, Milk Chocolate & Black & White. Susan Baca, my cousins mother in law is a cupcake connoisseur, so I was desperate to find some recipes for Sprinkle's cupcakes. Here is what I found:

10 oz. bittersweet chocolate, chopped
1 lb. unsalted butter, at room temp
1 lb. 8 oz. powdered sugar
1/8 tsp. salt
1 tsp. pure vanilla extract
1/2 cup sour cream

Melt and cool chocolate (until just slightly warm). (I like to melt chocolate in a double boiler over a medium low heat)

Beat butter until light and fluffy. With mixer on low speed, gradually add powdered sugar. Add salt, vanilla and sour cream and mix until very smooth. Add chocolate and mix until just incorporated.

*Don't over-whip and add too much air into the frosting. The consistency should be rich and dense, like ice cream!