Beat 175g unrefined caster sugar with 175g butter. Add 3 eggs, beating well.
Add 175g self raising flour, and 1 tsp baking powder.
Mix up 4 tsp instant coffee dissolved in 2 tbsp boiling water. Add half the mix to the bowl. Fold in.
Divide between two sandwich tins and bake till well risen and golden brown. Turn out and cool on wire rack.
Cream 100g butter with 225g icing sugar and the remaining coffee mixture, and use half this mixture to sandwich the cake together, the other half on the top of the cake.
Variation: Add 75g walnuts to the mixture and press walnuts into the icing on top.