The recipe –
1. Preheat your oven to 180°C/160°C fan/gas 4. Grease two 20cm/8-inch cake tins.
2. Cream together butter and the sugar until very pale and creamy, then gradually beat in the egg and vanilla essence. Stir in half of the black coffee. Some people enjoy licking the wooden spoon at this point…
3. Using a metal spoon, fold in the flour and baking powder in a figure-of-eight motion. This will keep the air in to give you a lovely light cake!
4. Fold in the finely chopped walnuts, then divide the mixture between the tins and spread evenly.
5. Bake for 25–30 minutes, or until a skewer inserted into the cakes comes out clean and the surface is golden on top – don’t forget to enjoy the lovely coffee smell! Carefully turn out the cakes on to a wire rack.
6. Drizzle the cakes with the remaining coffee and allow to cool.
7. Meanwhile, get to work on the filling: beat together the icing sugar, cream and mascarpone cheese until very smooth.
8. Once the cakes have cooled, sandwich together with two-thirds of the filling mixture. Spread the remainder over the top and arrange the walnut halves around the edge. A final flurry of coffee powder dusted on top will give it that extra special finish!
9. Serve immediately or keep in the fridge for up to two days.