Can I Use Buttercream On The Chocolate Guinness Cake?

Our answer

NIgella's Chocolate Guinness Cake is not a particularly sweet cake and the Guinness gives it a slightly ferrous tang. It is topped with a frosting made from cream cheese, lightened with cream. Whilst this frosting is light and airy, it may not cling particularly well to the sides of a cake.

Buttercream would probably be the best option and you could look at using a Swiss meringue or Italian meringue buttercream, as these tend to be slightly less sweet than a basic butter and icing (confectioners') sugar buttercream. Also, given that the cake itself is pretty dark in coiour, you may be able to do a very thin coating of buttercream around the edges of the cake, almost in the style of a "naked" cake, if you are worried about it being too sweet. However, we would suggest sticking to the whipped cream and cream cheese frosting for the top, emulating the "head" of a pint of Guinness.