Ingredients

Step by step

1. Preheat the oven to 180°C, fan 160°C, gas 4. Butter a 20cm round cake tin that is at least 5cm deep, and line the base with baking paper.

2. Spread the hazelnuts out in a small baking tin and toast in the oven for about 10 minutes until lightly golden. Coarsely chop the nuts in a food processor until they resemble rubble. Don’t blend them too far, you want them asquite identifiable chunks.
3. Beat the butter and sugar together with an electric mixer until pale and light. Add the egg yolks, one by one, beating well.
4. In a separate large bowl, beat the ricotta lightly with a fork. Add the lemon zest and chopped nuts. In a third large bowl, whisk the egg whites with a clean dry whisk until they form soft peaks.

5. Fold the egg yolk and butter mixture into the ricotta. Sift in the flour and fold it in. Finally, fold in the whisked egg whites, starting with one spoonful to loosen the mixture, then add the remainder, being careful not to over mix. Spoon into the prepared cake tin and bake for 25 minutes or until set.

6. Remove the cake from the tin to a plate and leave for 5 minutes, then whilst it is still warm, cover with the grated chocolate, which will immediately melt.
   
   Recipe taken from River Cafe 30 by Ruth Rogers, Rose Gray, Joseph Trivelli and Sian Wyn Owen (Ebury Press, £28). Available from 5 October