Heat a large heavy-bottomed pan over medium-high heat. Cook the finely diced pancetta (bacon or guanciale) until the fat is rendered and it just begins to brown.
Add the ground beef and pork, season with salt, and cook until the meat starts to get dark and caramelized, breaking up any large chunks with a wooden spoon.
While the meat is browning, finely chop the onion, celery, and carrot, either by hand or using a food processor, the latter being my preference. (The super finely diced vegetables will disappear into the sauce once it’s done cooking.)
Add the vegetables to the browned meat and cook until softened and most of the moisture has evaporated, about 10–12 minutes.
Stir in the minced garlic, fennel seeds, rosemary, and sage. Cook for 2–3 minutes, until fragrant. Be careful not to let the garlic burn.
Add your vermouth and scrape the bottom of the pan to loosen any browned bits. Let it cook until most of the liquid has evaporated.
Stir in the milk and add just enough water to cover the meat. Bring to a simmer, then partially cover and reduce the heat to low. Let the ragù simmer gently for 2 ½ to 3 hours, stirring occasionally. Add a splash of water if it begins to get too dry.
Once the sauce has finished cooking, taste and adjust seasoning if needed. It may need some extra salt.
Just before serving, stir in the heavy cream (if using) and toss the ragù with your cooked pasta and a splash of starchy pasta water. The sauce should be rich, creamy, and cling to the pasta.
Top with freshly grated Parmesan and serve immediately.