Coffee, white chocolate & walnut cake

Grease 3 x 18cm round sandwich tins with butter and line the bases with baking parchment. Preheat the oven to 180°C, gas mark 4. Cream together the butter and sugar until pale and fluffy, about 4-5 minutes, using a stand mixer or electric hand mixer. Beat in the eggs, 1 at a time.

In a separate bowl, combine the flour and baking powder, then gradually add to the butter and egg mixture, followed by the coffee, until a thick batter forms. Stir in the milk to loosen it slightly.

Divide the mixture evenly between the tins and use a spatula to smooth the top. Bake for 20-25 minutes, or until the cakes are risen, deep golden and a skewer inserted into the centre comes out clean.

For the topping, melt the white chocolate in a bowl over a pan of simmering water, or in the microwave on a low setting, stirring often until smooth. Pour onto a sheet of baking parchment. Spread out into a large rectangle using a palette knife, then sprinkle over the walnut halves, crushing a few over the top for a different texture. Allow to harden at room temperature or in the fridge.

For the icing, put the mascarpone, white chocolate, coffee and milk into a large bowl. Using an electric hand mixer, beat for a few minutes, or until light and spreadable.

Assemble the cake, spreading ⅓ of the icing between each layer and ⅓ on top. Break up the white chocolate and walnut slab into shards and arrange on top of the cake. This will keep for 3-4 days in the fridge.