2) For the ragu: Heat the oil in a wide, medium-sized saucepan, and fry the pancetta until beginning to crisp.
3) Add the lamb breaking it up with a fork in the bacony pan as it browns.
4) Tip in the caramelized onions, Marsala, tomatoes, lentils and water and bring the pan to the boil.
5) Simmer the ragu for 20 minutes stirring occasionally. Sprinkle over the cheese before serving, if using.
Recipe from Nigella Express by Nigella Lawson (published by Chatto & Windus) Visit Nigella's site.