IrishPalaver: Nigella's Chocolate Guinness Cake

Hi all -- long time no blog!   But I had to come back to wish you a happy St. Patrick's Day, and to suggest this delicious chocolate Guinness cake, courtesy of Nigella Lawson.   You bake the moist cake -- made with cocoa, butter, Guinness, and sour cream -- in a springform pan, and then top with icing made from confectioner sugar, cream cheese, and heavy cream, so that, as NIgella says, "it resembles a frothy pint of Guinness."  Cheers!