Marcella Hazan's Bolognese Sauce is a classic Italian meat sauce that is rich, hearty, and full of flavor. Made with a combination of ground beef, pancetta, onions, carrots, celery, tomatoes, milk, and wine, this sauce is simmered for hours to develop its deep, complex flavors. It is perfect for serving over pasta, and can also be used in lasagna or as a filling for stuffed pasta shells. This recipe is a true Italian classic that will impress your family and friends.