100 g walnuts
140 g golden caster sugar
3 tbsp milk, heated
2 tsp instant coffee granules
100 g salted butter, softened
2 tbsp walnut oil
75 g self-raising flour
75 g plain wholemeal flour
½ tsp bicarbonate of soda
350 g unsalted butter, softened
400 g icing sugar
2 tbsp cocoa powder
2 tbsp instant coffee granules (mixed with 4 tbsp boiling water to dissolve)
1 tsp vanilla extract
- Heat the oven to 180C/fan 160C and line a 12-hole muffin tin with muffin cases. Put the walnuts in a food processor with about half the sugar and whizz until very finely chopped (like almond meal).
- Mix the milk and coffee to dissolve the coffee (if it needs some help, pop it in the microwave for a few seconds).
- Tip the walnut-sugar mix, remaining sugar, milky coffee, soft butter, oil, eggs, flours and bicarb into a large mixing bowl and beat with an electric whisk until smooth. Divide between the cases then bake for 18 minutes, or until golden and risen, and a skewer poked into the centre comes out clean. Cool for 5 minutes in the tin, then lift the cakes onto a wire rack to cool completely.
- For the icing, put the butter in a big mixing bowl and beat for about 5 minutes until very pale and creamy. Sift in the icing sugar and cocoa then add the coffee and vanilla and beat for another 3-5 minutes until very fluffy.
- To decorate, put the icing into a large piping bag fitted with a star nozzle. Pipe swirls of icing on top of each cake, then leave to set for 20 minutes before eating.