125g (4oz) unsalted butter, softened
1 cup (250g/8oz) caster sugar - I reduce to 200g
3 eggs, lightly beaten
1 tsp vanilla essence
1tbsp instant coffee powder
¾ cup (90g/3oz) plain flour
½ cup (60g/2oz) self-raising flour
1/3 cup (90g/3oz) sour cream
1. Preheat over to warm 160ºC (315 deg F/ Gas 2-3). Lightly grease a 7inch square cake tin and line with baking paper.
2. Cream the butter and sugar until light and fluffy. Add the egg one at a time, beating thoroughly after each addition. Dissolve the vanilla and coffee powder in 1 tablespoon warm water and beat into the mixture until well combined. Fold in sifted flours alternately with the sour cream. Stir until the mixture is just combined and almost smooth.
3. Spoon mixture into the tin and smooth the surface. Bake for 30-40minutes, or until skewer comes out clean when inserted into the centre of the cake. Leave the cake in the tin for 5 min before turning out onto wire rack to cool completely.