Beat together the sugar and eggs until pale and thick. Add the sifted flour and baking powder, craisins, nuts and chocolate and stir until well combined. Turn out onto a lightly floured surface and knead until smooth
Divide the mixture in half and shape into two 30cm x 5cm logs. Place on lined baking trays and bake in a moderate oven 180°C for 25-30 minutes until lightly browned and firm to touch. Allow to cool for 10 minutes
Reduce the oven to 150°C. Using a serrated knife, cut the logs on a slight diagonal into 1cm thick slices, then lay them cut side down on the tray and bake for 10 minutes. Turn the biscotti over and bake for a further 10 minutes. Cool completely and store in an airtight container for 2-3 weeks