Heat the oil in a tall sauce pot over medium-high heat. Brown the meats separately (bacon, pork shoulder, sausage), and set them aside in a covered bowl. Watch out for overbrowning of the crystallization; you might have to wash out the pan if it gets too dark. In the browning oil, cook the vegetables (onions, garlic, carrots, celery) until the vegetables are slightly soft. Throw in the herbs (thyme, bay, pepper) and cook for a minute or so. Add some salt, but remember to add less if youâre using canned stock. Add liquids (wine, stock, tomatoes) and the browned meats. Add enough water that the meat isnât poking out of the sauce. Bring to a boil and then cut back to a bare simmer. Cover and cook for two hours. Skim excess fat occasionally. Using a wooden spoon, find the pork cubes and press them against the side of the pot, so that they come apart into individual fibers. Leave the sausage alone. Simmer for a while longer, and make a final adjustment for consistency and seasoning. This sauce gets better if it sits for a couple of days, but can be used immediately. To assemble: Butter a 9 x 13â dish. Add the ingredients in layers: half the pasta, the provolone, the sour cream, half the sauce, the rest of the pasta, the mozzarella, the rest of the sauce, and finally the parmesan. Cover and set aside or refrigerate if it will be a while. To cook: Preheat oven to 400°F and cook uncovered for 15 min or until the cheese is browned on top, at which point cover it loosely with foil. Cook until warmed through, around 15-20 minutes more. Rest for 10-15 minutes before cutting.