Place the light coloured biscuit dough onto a large oven tray. Using your hands, roll into a 30 cm long log shape. Place dark coloured biscuit dough onto same tray and roll into a 40 cm long log shape. Then twist dark dough around the light dough to create a swirl pattern. Using your hands, roll the log until smooth and both dough have come together. Refrigerate dough on oven tray for 2 hours, or until firm.