Break off about a third of the dough. Shape the larger into a ball and place on the baking sheet. Shape the smaller piece into a ball. Brush a little water on the centre of the larger ball and place the smaller ball on top. Use a floured finger to press all the way down through the centre of the dough, as far as possible, so it almost touches the baking sheet. Use the tip of a knife to score lines about 5 mm deep through the dough, marking it into 12 wedges.