Chocolate Cake "Flourless Chocolate Mousse Cake "

Begin by making the chocolate sponge in a cake tin (preferably a springform one, 15cm diameter). Cut a circle of greaseproof paper to cover the tin’s base, and lightly butter the paper on both sides.

Separate the eggs – yolks in one bowl, whites in another. In a food mixer on full power, whisk the egg whites to firm peaks, adding the sugar little by little. Take a third of the whisked egg whites and whisk them into the egg yolks. Once incorporated, gently fold in the remaining whisked whites. Now sift and fold in the cocoa powder. Pour the mixture into the prepared cake tin and spread it evenly with a spatula or palette knife. Bake for 18–20 minutes, or until a skewer inserted into the middle comes out clean. Allow the sponge to cool before removing it from the tin. Leave it to cool on a wire rack.

Clean the cake tin. Carefully remove the paper from the base of the sponge. Now put the cooled sponge back in the ring, ready to have the chocolate mousse mixture poured over it. Chop the chocolate into bite-sized pieces and melt them in a large heatproof bowl in a saucepan of gently simmering water. The melted chocolate should be hot to the touch to ensure it is well incorporated in the next stage. Sift the cocoa powder into a separate bowl and whisk it with the egg yolk and hot water. Pour this onto the melted chocolate but do not mix.

Next, whisk the egg whites and sugar to medium peaks. Briskly whisk about a third of the whisked egg whites into the melted chocolate, and then fold in the remaining egg whites. Pour the mousse mixture onto the chocolate sponge in the ring. Transfer it to the fridge to set for at least 3 hours.

To remove the flourless chocolate mousse cake, heat a palette knife in a bowl of hot water, wipe it with a clean tea towel, and then slide it around the inside of the tin. Before serving, decorate with a dusting of cocoa, a sprinkling of grated chocolate and chopped toasted pistachios or almonds, if using.