Experienced cake makers will notice that the method for making this cake from Lombardy is quite unusual. Here, all the ingredients are added to beaten egg whites, not the other way around, which gives it quite a distinct texture.
130g/4½oz/generous ½cupunsalted butter, cubed, plus extra for greasing
250g/9oz dark/bittersweet chocolate, chopped
5 large/US extra large eggs, separated
1espresso (about 30ml/2tbsp very strong black coffee)
200g/7oz/1cup caster/superfine sugar
30ml/2tbspunsweetened cocoa powder
400g/14ozchocolate, melted, to cover
Preheat the oven to 180°C/350°F/Gas 4. Grease and line a 23 cm/9 in loose-based cake tin or pan with baking parchment.
Melt 250 g/9 oz of the chocolate in a heatproof bowl over a pan of gently simmering water. While the chocolate is melting, put the egg whites into a clean, grease-free bowl and whisk until they form stiff peaks. Remove the melted chocolate from the pan and stir in the butter, then add the coffee.
Carefully fold the sugar into the egg whites. Measure the baking powder with the cocoa powder and flour into a bowl. Stir the egg yolks into the melted chocolate mixture, then gently fold this mixture into the egg whites.
Sift over the baking powder, cocoa powder and flour mixture and gently fold in with a large metal spoon until the dry ingredients are completely incorporated, but taking care not to knock out too much air. Turn into the prepared tin.
Bake for 40 minutes, or until a skewer inserted into the middle comes out clean. Leave to cool in the cake tin.
Melt the remaining chocolate in a heatproof bowl over a pan of gently simmering water. Turn out the cooled cake and cover with melted chocolate. Leave to set before serving.