Ingredients
For the Cake:
250g good quality dark chololate (minimum 70% coco solids)
125g unsalted butter, softened
6 eggs:- 2 whole and 4 separated
175g caster sugar
2 tablespoons Cointreau (optional) grated zest of 1 orange (optional)

For the Cream Topping:
500ml pure double cream
1 teaspoon vanilla extract
1 tablespoon Cointreau (optional)
2 teaspoons brown sugar
½ teaspoon cocoa powder for sprinkling
freshly grated nutmeg for sprinkling (optional)


Method
Preheat oven to 180°C. Line the bottom of the springform cake tin with baking paper. Melt chocolate gently in a double boiler and then let the butter melt into it whilst stirring.

Beat 2 whole eggs and 4 egg yolks with 75g of the caster sugar until firm and fluffy. Add the chocolate mixture, Cointreau and orange zest and beat to combine.

In another bowl, beat the 4 egg whites until foamy, then gradually add the remaining 100g castor sugar. (Note, that you will need to clean the beaters in between as if they still have any egg yolk chocolate mixture on them the egg whites will not stiffen up properly). Beat until whites hold their shape, but are not too stiff. Lighten the chocolate mixture by folding in a large dollop of the egg whites and then fold in the rest of the egg whites. Pour into the prepared tin and then bake for 35-40 minutes, or until the cake has risen and is cracked, and the centre is no longer wobbly. Cool the cake in its tin on a wire rack. The centre will sink considerably, but don't worry as it's the crater-look we are after. When the cake is cold, slide a knife around the edge of the tin before removing the cake.

Whip the cream and brown sugar until soft, then add the vanilla and Cointreau. Continue to whisk until firm but not stiff. Fill the crater of the cold cake with the whipped cream. Dust the top with coco powder pushed through a tea strainer and a little grated nutmeg if you wish.