Prep 20 mins
Cook 35 mins
When it comes out of the oven the cake should still be moist in the middle. As it cools the cake will sink slightly and the crust will crisp. On cooling, the outside of the cake becomes sponge like, while the centre remains dense and fudgy.
- Line the base of a 21-23cm shallow springform cake tin with silicone baking parchment, buttering the tin lightly to hold it in place.
- Melt the chopped chocolate in a heatproof bowl set over a pan of simmering water.
- As soon as it starts to soften, add the coffee and leave it for two or three minutes.
- Stir very gently, then when the chocolate has melted add the butter.
- Stir until it has melted.
- Meanwhile, beat the egg with an electric mixer till stiff, then fold in the sugar.
- Mix the baking powder with the cocoa powder and flour.
- Remove the chocolate from the heat, quickly stir in the egg yolks, then slowly, firmly and gently fold the melted chocolate into the egg whites.
- Lastly sift in the flour and cocoa mixture.
- Stir the mixture with a large metal spoon, taking care not to knock out any air.
- It should feel light and wobbly.
- Do not overmix- just enough to fold in the flour.
- Scoop into the lined tin and bake in an oven preheated to 180 C for 35 minutes.
- Leave to cool in its tin, then turn out.