This is an extraordinary frosting. It's more work, but oh the results! Use this for the Double Down Chocolate Cake recipe I posted. Thanks to Cook's Illustrated for this one. If you like this recipe, see others at mybestcookbook.wordpress.com
Melt the chocolate chips in the microwave or double boiler. Set aside.
Beat the rest of the ingredients except for the cream until light and fluffy.
Remove bowl from mixer and add the chocolate and whisk in. Add the cream and sit bowl in an ice bath and stir until frosting has reached room temperature. (you can fudge on this, and just let it cool naturally, whisking from time to time.)
Frost the cake and then shave the chocolate bar over the top.