Pre-heat oven to 180°C (160°C fan-forced). Line a large oven tray with baking paper.
Place sugar and eggs into the bowl of an electric mixer, beat until pale and creamy. Fold in the flours and baking powder. Remove bowl from the mixer and use a large spoon to mix in the nuts and cranberries.
Tip mixture onto a lightly floured surface and bring together as a dough. Divide into two portions, rolling each into a log approximately 28 x 5cm. Place onto the oven tray allowing space between for a little spreading. Bake for 30 minutes, remove from the oven and allow to cool for 1 hour. Reduce oven temperature to 120°C (100°C fan-forced).
Cut each log on a slight diagonal into ½ cm thick slices and place onto lined oven trays cut side down. Bake for 5 minutes, turn over and cook for a further 5 minutes. Remove from the oven tray and allow to cool completely on a wire rack.
Once cooled, dip one end of each biscotti into the melted chocolate and allow to set on a wire rack.