In a large Dutch oven or heavy bottom pot, add the olive oil and butter over medium heat. In a food processor, pulse the onion, celery, and carrot until finely chopped. Cook, stirring occasionally, until the vegetables are soft and golden, about 5-7 minutes.

While the vegetables are cooking, add the tomatoes with their juice to the food processor and pulse 5-7 times until smooth. Transfer to a bowl and set aside. Wipe out the food processor, then add the pancetta to the bowl. Pulse until the pancetta is a coarse paste. Set aside.

Add the ground chuck, pork, and pancetta to the Dutch oven, along with the red pepper flakes. Use a wooden spoon to break the meat apart as it cooks, just until lightly browned so the meat loses its raw edge. Add the tomato paste and cook for about 10 minutes until the paste begins to brown, stirring when needed so it doesn't burn.

Add the wine and cook until the wine is almost all absorbed, about 10 minutes, stirring to scrape up any browned bits. Add the milk and cook until it has evaporated, which will take about 30 minutes, stirring and breaking up the meat more as it cooks.

Add the tomatoes, broth, bay leaves, and kosher salt. Bring to a simmer then reduce the heat to the lowest setting so it cooks with barely a bubble breaking the surface occasionally. Cook for 2 ½ to 3 hours until the meat is tender and the sauce has reduced and thickened to become rich and dark in color. Toward the end of cooking, a layer of oil will likely rise to the top. Spoon off the oil or fold back into the sauce as desired. The longer you cook the sauce the better it will become. If the sauce seems to dry out, add ¼ cup hot water at a time as needed.

Serve the sauce over wide egg or pasta noodles such as pappardelle, tagliatelle, fettuccine, or rigatoni. Serve topped with fresh grated Parmesan cheese/