the chocolate into small pieces and tip into a heatproof bowl. Pour the butter mixture over the dark chocolate and stir until the chocolate is melted and shiny. Leave to cool, cover with clingfilm and refrigerate until firm. Making one truffle at a time, scoop a

into the middle of the cake comes out clean. The medium cake should take about 30 minutes and the large cake should take 30–35 minutes.Remove the tins from the oven and leave to cool for 10 minutes before tipping the cakes out onto a wire rack to cool.To make