Classic lasagne

Instructions

1. To make the ragù, heat the oil in a large, lidded, nonstick pan and add the beef. Cook over a medium-high heat for 8–10 minutes, breaking up the meat with a wooden spoon as it cooks. Once the mince is nicely browned, remove it using a slotted spoon and set aside.
2. Cook the pancetta in the same pan for around 5 minutes, or until golden. Remove with a slotted spoon and set aside. Add the onion, celery and carrots to the pan. Cover and cook over a low heat for 10 minutes, or until softened. Add the garlic and cook, uncovered, for 2 minutes.
3. Return the beef and pancetta to the pan and add the tomatoes, tomato purée, sugar, oregano and stock. Bring to the boil and simmer for 30 minutes, or until thickened and rich. Season to taste, taking care not to add too much salt.
4. Meanwhile, make the white sauce: put the milk in a small saucepan with the peppercorns, parsley and bay leaf. Slowly bring just to the boil, then remove from the heat and allow to infuse for 10 minutes before passing through a sieve into a jug to remove the herbs. Return the strained milk to the pan.
5. Mix the cornflour with a splash of cold water into a smooth paste. Pour some of the warmed milk over and whisk. Add this mixture to the milk in the pan and whisk again. Slowly bring to the boil, whisking, until the sauce has the consistency of pouring cream. Remove from the heat, mix in the mustard and season to taste.
6. Preheat the oven to 180ºC, fan 160ºC, gas mark 4. Spoon half the ragù into a 2-litre lasagne dish and top with a layer of lasagne sheets. Spoon around a third of the white sauce over and top with the remaining ragù. Add a final layer of lasagne sheets and the remaining white sauce. Scatter the Parmesan over and bake for 45 minutes, or until golden and bubbling and the pasta is tender.