Prepare the Vegetables:
Heat the olive oil in a large heavy-bottomed pot or Dutch oven over medium heat.
Add the finely chopped onion, carrots, and celery. Sauté until the vegetables are soft and translucent, about 8-10 minutes.
Add the minced garlic and cook for an additional 1-2 minutes until fragrant.
Cook the Meat:
Add the ground beef and ground pork to the pot. Break the meat apart with a wooden spoon or spatula and cook until browned and no longer pink, about 10 minutes.
Drain any excess fat if necessary.
Add the Milk:
Pour in the whole milk and stir to combine. Allow the milk to simmer until it has mostly evaporated, about 5-7 minutes. This step helps tenderize the meat.
Add the Wine and Tomatoes:
Pour in the red wine and stir to combine. Let it simmer until the wine has mostly evaporated, about 5-7 minutes.
Add the crushed tomatoes and tomato paste. Stir to combine.
Season and Simmer:
Add the dried oregano, dried basil, dried thyme, and crushed red pepper flakes (if using). Season with salt and freshly ground black pepper to taste.
Reduce the heat to low, cover the pot, and let the sauce simmer gently for 1.5 to 2 hours, stirring occasionally. The longer it simmers, the more the flavors will develop.
Finish the Sauce:
Stir in the chopped fresh parsley and grated Parmesan cheese. Adjust the seasoning with more salt and pepper if needed.
Cook the Pasta:
While the sauce is simmering, cook the pasta according to the package instructions until al dente. Drain and set aside.
Serve:
Toss the cooked pasta with the Bolognese sauce until well coated. Serve hot with extra grated Parmesan cheese on the side.