Lightly grease two baking trays. Roll out the dough on a lightly floured surface to a thickness of about 8mm/3/8 inch and cut out heart shapes, using a biscuit cutter. Transfer the shapes to a baking tray, spacing them slightly apart. Re-roll the trimmings to make more biscuits. Bake in a preheated oven, 180 oC/350 oF/Gas Mark 4 for about 10-15 minutes until slightly risen. Transfer to a wire rack and leave to cool.