In a large pot or Dutch oven, heat olive oil over medium heat. Add the chopped onion, carrots, and celery. Cook for about 8 to 10 minutes until the vegetables are soft and lightly golden.
Stir in the minced garlic and cook for 1 to 2 minutes until it smells fragrant.
Add the ground beef and ground pork. Break up the meat using a spoon. Season with salt and pepper. Cook for 10 to 12 minutes until the meat is fully cooked and browned.
Pour in the milk and let it simmer for around 5 minutes until mostly absorbed. Then add the white wine and simmer for another 5 minutes.
Stir in the crushed tomatoes, diced tomatoes, tomato paste, bay leaves, and oregano. Bring everything to a gentle boil, then lower the heat to a simmer. Cover the pot, leaving a small space for steam to escape.
Keep the sauce simmering on low heat for 2 to 3 hours. Stir once in a while. If the sauce becomes too thick, you can add a little water or chicken broth.
Remove the bay leaves. Stir in the grated Parmesan cheese. Taste and adjust the salt and pepper if needed.
Serve the sauce over your favorite pasta like spaghetti or pappardelle. Sprinkle with chopped parsley if you like.