Ingredients

Step by step

1. Preheat the oven to 170°C, fan 150°C, gas 3. Grease and line the base and sides of a 23cm round cake tin with baking paper.
2. Put the dark chocolate pieces into a heatproof bowl and rest over a small pan of barely simmering water. Leave until melted then leave to cool slightly.
3. Put 225g of the walnut halves into a food processor and whiz briefly until finely chopped. Add the plain flour, baking powder and salt and whiz briefly once more until finely ground.
4. Cream the butter and sugar together in a large mixing bowl for 5 minutes until light and fluffy. Beat in the vanilla then add the eggs one at a time, adding 1 tablespoon of the walnut and flour mixture with the second and third eggs.
5. Fold in half the remaining nut and flour mixture, then the cooled melted chocolate, followed by the remaining nut and flour mixture.
6. Spoon the mixture into the prepared tin and level the surface, then arrange the remaining walnut halves on the top in concentric circles, working from the outer edge towards the centre. Bake for 45-55 minutes (cover loosely with a double thickness of foil once it is nicely browned) until a skewer pushed into the centre of the cake comes out slightly sticky (as for a brownie).
7. Leave the cake to cool completely in the tin, then unmould from the tin and transfer to a cooling rack.
8. For the drizzle, if using, melt the milk chocolate as before, then use a teaspoon to drizzle over the cake. Let it set before slicing to serve.
   Tip

   Make it gluten free
   Use GF flour and baking powder, adding ½ tsp xanthan gum with the nut and flour mixture, plus 3 tbsp milk to loosen the batter.