For the icing, sift the golden icing into a small bowl. Add boiling water a teaspoon at a time, beating well. When you have a thickish but still runny consistency, pour the icing onto the cakes allowing the icing to just drip over the sides. Leave to set before serving. Why not try swapping the lemon zest and juice for the zest and juice of ½ an orange and fill with a buttercream flavoured with a touch of rose water.