In a large skillet, Dutch oven, or stovetop safe slow cooker insert, heat the butter and olive oil. Add the ground beef, pork, and pancetta or bacon, along with the onion, carrot, and celery. Cook, stirring frequently, until the beef and pork are no longer pink. Stir in the garlic and cook, stirring, for 5 minutes longer. Stir in the tomato paste and red wine. Cook, stirring frequently, for 5 minutes.
To the sauce mixture add the, crushed and diced tomatoes, salt, pepper, bay leaves, and basil. Bring to a simmer.
Transfer the sauce to the slow cooker; cover and cook on HIGH for 2 to 3 hours.
Add the cream Parmesan cheese and cook for 30 to 45 minutes.