Melt butter in a large stockpot or Dutch oven over medium heat. Add onion, carrot and celery. Cook, stirring occasionally, until tender, about 3-4 minutes.
Add ground beef, ground pork, pancetta, 1 teaspoon salt and 1/2 teaspoon pepper. Cook until browned, about 5-8 minutes, making sure to crumble the beef and pork as it cooks; drain excess fat.
Stir in tomato paste, garlic, oregano, red pepper flakes, nutmeg and cinnamon until fragrant, about 1 minute.
Stir in wine, scraping any browned bits from the bottom of the pot.
Stir in milk. Bring to a boil; reduce heat and simmer until reduced, about 5 minutes.
Stir in crushed tomatoes. Bring to boil; reduce heat and simmer, covered and stirring occasionally, until thickened and flavors have blended, about 20 minutes.
Stir in parsley; season with salt and pepper, to taste.*
In a large pot of boiling salted water, cook pasta according to package instructions; drain well.
Serve immediately with bolognese sauce.
Notes
*TO FREEZE: Let cool completely; portion into plastic freezer bags in individual servings, squeezing out any excess air before sealing. Lay the bags flat in a single layer in the freezer (this will help them freeze quickly). To reheat, thaw overnight in the fridge, reheating over low heat, stirring occasionally, until heated through.