Equipment and preparation: You will need a large piping bag fitted with a 1.5cm/½in fluted nozzle and a 0.5cm/¼in nozzle. For the choux pastry For the filling 20g/¾oz unsweetened chocolate, 100% cocoa solids 450g/1lb pastry cream (crème patissière), at room temperature (see Top recipe tip below) 1 tbsp strong cocoa powder, sifted For the glaze Preheat the oven to 170C/325F/Gas 3.