The pages of our copy are stained with the residue of many cakes.

Nigel says when it comes out of the oven the cake should still be moist in the middle. As it cools it will sink slightly and the crust will crisp.

180g fine dark chocolate, chopped
a small espresso (about three tablespoons of very strong coffee)
140g unsalted butter, diced
five free range eggs, separated
200g golden caster sugar
one teaspoon baking powder
two tablespoons cocoa powder
90g plain flour

Preheat the oven to 180°C.  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 whites 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 tenderly with a large metal spoon, taking care not to knock out any air.  It should feel light and wobbly.  Do not over mix – just enough to fold in the flour.  Scoop into the lined tin and bake in an oven preheated to 180°C for thirty-five minutes.  Leave to cool in its tin then turn out.

Nigel Slater: Real Food, page 309