8. Pour the cooled chocolate mixture over the eggy mousse, then gently fold together with a rubber spatula. Plunge the spatula in at one side, take it underneath and bring it up the opposite side and in again at the middle.
Continue going under and over in a figure of eight, moving the bowl round after each folding so you can get at it from all sides until the two mixtures are one and the colour is a mottled dark brown.
The idea is to marry them without knocking out the air, so be as gentle and slow as you like.
7. Hold the sieve over the bowl of eggy chocolate mixture and resift the cocoa and flour mixture, shaking the sieve from side to side, to cover the top evenly.
8. Gently fold in this powder using the same figure of eight action as before. The mixture will look dry and dusty at first, and a bit unpromising, but if you keep going very gently and patiently, it will end up looking gungy and fudgy.
Stop just before you feel you should, as you don’t want to overdo this mixing.
9. Finally, stir in the white and milk chocolate chunks until they’re dotted throughout.