200g/7oz whole blanched hazelnuts

200g/7oz butter, cubed

200g/7oz dark chocolate, broken into squares

6 large eggs, separated

200g/7oz sugar

3 T. orange juice

Preheat the oven to 350 deg F. Grease a 9 in. springform cake tin and line the base with baking parchment.

Place the hazelnuts in a food processor and blend them until they are fairly finely ground. Blend the nuts to the consistency of fine breadcrumbs, but leave a few coarser pieces to add texture.

Place the butter and chocolate in a large measuring cup and microwave until melted, stirring every 30 seconds. Stir in the ground hazelnuts and leave the mixture to cool for 5 minutes.

Beat the egg yolks and sugar together with an electric hand-whisk for at least 5 minutes until pale and creamy, then stir into the chocolate mixture until thoroughly combined. Wash and dry the beaters well.

In a clean bowl, whisk the egg whites until stiff peaks form – they are ready when you can turn the bowl upside down without the eggs sliding out. Do not over whisk.

Working quickly, stir the orange juice, into the chocolate mixture to soften. Add a couple of tablespoonfuls of the whisked egg whites and stir until thoroughly combined, then gently fold in the remaining egg whites.

Spoon the mixture into the prepared tin and bake in the centre of the oven for 35–40 minutes or until the cake is well risen and firm.

If making this sugar-free, use sugar-free dark chocolate, and replace the 7 oz. of sugar with 1 1/2 times the amount of Splenda (by volume, not by weight). Use the three small springform pans instead of the big one.

BBC Food: Chocolate Hazelnut Cake