Rose Levy Beranbaum demonstrates how to make a simple and delicious chocolate ganache frosting, and gives tips for frosting the cake. Only two ingredients are needed - 12 ounces of semi-sweet or bittersweet chocolate, whichever you prefer, and 1 2/3 cups of heavy cream. Grate the chocolate in the food processor, then with the motor running pour in the cream, and it's done. However, it needs to sit for a few hours to thicken. You can refrigerate it but don't stir it. When you're ready to frost the cake, start with a large dollop of frosting so it doesn't lift the crust off the cake. A turntable makes the frosting easier. If you will be putting on a top layer it's a good idea to freeze the frosted layer for five minutes to set it. Place the top layer on carefully and frost the top first. Then using large dollops of frosting, cover the sides, using a back and forth motion with the spatula. When you're done you will have a beautifully frosted cake.