1. Preheat the oven to 180C/Gas 4. Grease and base line two 20cm sandwich tins. Sieve the flour and baking powder into a bowl. Add the butter, sugar and eggs, then whisk until the mixture is soft and smooth.
2. Fold in the coffee mixture and walnuts; spoon into the tins. Cook on the middle shelf for 30 minutes, until firm to the touch. Leave in the tins for 5 minutes, then turn out on to a wire rack. Fold in the coffee mixture and walnuts; spoon into the tins. Cook on the middle shelf for 30 minutes, until firm to the touch. Leave in the tins for 5 minutes, then turn out onto a wire rack.
3. Meanwhile, cream the butter and mascarpone with the coffee. Add the icing sugar a spoonful at a time, mixing after each addition. Spread half over the first cake, place the other cake carefully on top and spread over the remaining mixture. Decorate with walnut halves.

Nutritional information per portion

• Calories 550(kcal)
• Fat 36.0g
• Saturates 17.0g
• Sugars 39.0g

This nutritional information is only a guide and is based on 2,000 calories per day. For more information on eating a healthy diet, please visit the Food Standards Agency website.

Guideline Daily Amount for 2,000 calories per day are: 70g fat, 20g saturated fat, 90g sugar, 6g salt.