100²µ/3½´Ç³ú plain flour, sifted
120²µ/4½´Ç³ú caster sugar
2 tbsp cocoa powder
icing sugar, for dusting
100²µ/3½´Ç³ú dark chocolate, chopped into small pieces
100²µ/3½´Ç³ú unsalted butter, softened, plus extra for greasing
crème fraîche, to serve
2 free-range eggs
2 free-range egg yolks