Twice-baked chocolate cake

Preheat the oven to 190 ­ºC, gas mark 5. Grease a 20­cm springform cake tin with butter and line with baking parchment. Melt the chocolate and butter together in a heatproof bowl set over a pan of barely simmering water, then transfer to a large mixing bowl to cool slightly.

Put the egg yolks in the bowl of a freestanding mixer or in a mixing bowl with 160­g sugar. Whisk together until fluffy using the whisk attachment or an electric hand mixer. In another bowl, use an electric hand mixer to whisk the egg whites and the remaining 100­­g sugar to soft peaks.

Add the egg yolk mixture to the chocolate mixture; stir together. Fold in the egg white mixture in 3 batches, then fold in the cocoa powder in 2batches. Pour ½ of the cake batter into the prepared tin and bake for 35-45 minutes until risen and a skewer comes out completely clean. Take out of the oven and leave to cool slightly. Turn the oven down to 180ºC, gas mark 4.

When the cake has cooled slightly, press the edges down gently to flatten. Pour the remaining cake mixture into the tin and bake for 25-30­ minutes until the outer edges have risen and the middle is just set and jiggly. Allow to cool in the tin completely before removing. Serve with a dollop of crème fraîche, if liked. Best eaten on the day it is made, but it can be wrapped and stored at room temperature for up to 3 days.