Chocolate Cloud Cake

From Nigella.com

Ingredients

• 250g dark chocolate, minimum 70% cocoa solids
• 125g unsalted butter, softened
• 6 eggs: 2 whole, 4 separated
• 175g caster sugar
• 2 tablespoons Cointreau (optional)
• Grated zest of 1 orange (optional)
• 23cm springform cake tin

FOR THE CREAM TOPPING:

• 500ml double cream
• 1 teaspoon vanilla extract
• 1 tablespoon Cointreau (optional)
• 1/2 teaspoon unsweetened cocoa powder for sprinkling

METHOD

Serves: 8-12.

1. Preheat the oven to 180°C/gas mark 4.
2. Line the bottom of the cake tin with baking parchment.
3. Melt the chocolate either in a double boiler or a microwave, and then let the butter melt in the warm chocolate.
4. Beat the 2 whole eggs and 4 egg yolks with 75g of the caster sugar, then gently add the chocolate mixture, the Cointreau and orange zest.
5. In another bowl, whisk the 4 egg whites until foamy, then gradually add the 100g of sugar and whisk until the whites are holding their shape but not too stiff.
6. Lighten the chocolate mixture with a dollop of egg whites, and then fold in the rest of the whites. Pour into the prepared tin and bake for 35-40 minutes or until the cake is risen and cracked and the centre is no longer wobbly. Cool the cake in its tin on a wire rack; the middle will sink as it cools.
7. When you are ready to eat, place the still tin-bound cake on a cake stand or plate for serving and carefully remove the cake from its tin. Don't worry about cracks or rough edges: it's the crater look we're going for here. Whip the cream until it's soft and then add the vanilla and Cointreau and continue whisking until the cream is firm but not stiff.
8. Fill the crater of the cake with the whipped cream, easing it out gently towards the edges of the cake, and dust the top lightly with cocoa powder pushed through a tea-strainer.

Comment: I don't put the cream on top unless I know it's all going to be eaten on the day it's served as otherwise it won't keep. I recently met a friend of a friend who had been at a dinner party where I cooked this... she couldn't remember my name, but she could remember the name of the cake.... As with all the richest recipes - Gluten Free.