This is a reassuringly easy cake to make, and very popular in my house, requiring nothing more taxing than beating wet ingredients into dry: in other words, just a bowl and wooden spoon number. And while you certainly don't need a processor to make the simple coffee buttercream, I loathe sieving, and this gets round the necessity of doing so. If you are making it by hand, however, sieve the icing sugar and beat with the butter until soft, before gently stirring in the hot coffee, to give you a smooth buff coloured icing. For US cup measures, use the toggle at the top of the ingredients list.