6egg yolks100 gmcaster sugar3gelatine leaves (titanium strength), softened in cold water for 5 minutes800 gmcrème fraîche250 gmraspberries, crushed, plus extra whole raspberries, to serveFor brushing:raspberry liqueurFor dusting:Dutch-process cocoaChocolate cake 240 gmdark chocolate (56% cocoa solids), coarsely chopped 130 gmbutter, coarsely chopped 12eggs, at room temperature450 gmcaster sugar360 gmplain flour90 gmDutch-process cocoa3 tspbaking powderChocolate truffle ganache380 mlpouring cream70 mlchocolate liqueur450 gmdark chocolate (56% cocoa solids), finely chopped6egg yolks
For chocolate cake, preheat oven to 180C. Melt half the chocolate and half the butter in a heatproof bowl placed over a saucepan of simmering water, stir occasionally until melted, keep warm. Whisk half the eggs and half the sugar in an electric mixer until pale and tripled in volume (5-6 minutes). Meanwhile, triple-sieve half each of the flour, cocoa and baking powder. Transfer egg mixture to a large bowl, sieve flour mixture over bowl in two batches, fold to combine. Fold in chocolate mixture, divide among three 20cm-diameter cake tins buttered and lined with baking paper and smooth tops. Bake, swapping tins between racks halfway through cooking, until centres spring back when lightly pressed (10-15 minutes), cool on a wire rack. Repeat with remaining ingredients to make six cakes. Wrap cakes individually in plastic wrap until required.
Meanwhile, for chocolate truffle ganache, bring cream and liqueur to the simmer in a saucepan over medium-high heat, remove from heat, add chocolate and stir until smooth and combined. Meanwhile, whisk yolks and 40ml hot water in a heatproof bowl over a saucepan of simmering water until pale and fluffy (2-3 minutes). Fold through chocolate mixture, transfer to an electric mixer and whisk until cooled to room temperature (10-15 minutes). Refrigerate until beginning to firm (45 minutes-1 hour).
Meanwhile, whisk yolks, sugar and 30ml water in a large heatproof bowl over a saucepan of simmering water until thick and pale (2-3 minutes). Squeeze excess water from gelatine, whisk to combine then remove from heat. Fold in crème fraîche and crushed raspberries then refrigerate until firm (30 minutes-1 hour).
Place a cake round on a serving plate, brush with raspberry liqueur and spread with chocolate truffle ganache to 5mm thick. Spread with one-fifth of raspberry crème fraîche mixture, top with another cake round. Repeat layers, finishing with a cake round. Spread remaining chocolate truffle ganache over top of cake and refrigerate until firm (30 minutes-1 hour). Serve dusted with cocoa and topped with extra raspberries.