A great flourless chocolate cake is essential to any baking
repertoire. This one is super-moist yet holds well for a long time.
It's important to cool it completely before it's served, or it may
crumble as it's sliced.
170 gmhazelnuts280 gmdark chocolate (66-70% cocoa solids), coarsely chopped100 gmbutter, coarsely chopped100 mlwell-shaken buttermilk at room temperature2 tbspDutch-process cocoa, sieved, plus extra for dusting6eggs, separated150 gmcaster sugar
Preheat oven to 190C, and butter a 22cm diameter cake tin and line with baking paper.
Roast hazelnuts on an oven tray until golden (5-8 minutes). While warm, tip into a tea towel and rub to remove skins, then finely chop.
Melt chocolate and butter in a heatproof bowl over a saucepan of simmering water, stirring occasionally until smooth. Remove from heat, and stir in buttermilk, cocoa and egg yolks.
Meanwhile, whisk eggwhites until frothy in an electric mixer, then, while whisking, gradually add the sugar and whisk until glossy soft peaks form. Fold in chocolate mixture in batches along with hazelnuts, pour into prepared tin and bake until cake rises and cracks at the top (25-30 minutes). Cool in tin, gently pressing on top as it cools so it falls back evenly, then remove from tin, dust with cocoa and serve. Cake will keep for 2-3 days stored at room temperature in an airtight container.