In a large pot or Dutch oven, heat the olive oil over medium-high heat. Add the ground beef and ground pork and cook, breaking up the meat with a spoon, until browned. Drain off any excess fat.
Add the chopped onion, carrots, and celery to the pot. Cook, stirring occasionally, until softened, about 8-10 minutes.
Stir in the minced garlic and cook for 1 minute more until fragrant.
Pour in the red wine and scrape up any browned bits from the bottom of the pot. Let the wine simmer and reduce by half, about 5 minutes.
Stir in the crushed tomatoes, tomato paste, beef broth, and milk. Add the oregano, nutmeg, and bay leaf.
Bring the sauce to a simmer, then reduce the heat to low, cover, and cook for at least 2 hours, or up to 3-4 hours, stirring occasionally. The longer it simmers, the richer the flavor.
Remove the bay leaf. Season with salt and freshly ground black pepper to taste.
Serve hot over your favorite pasta.
Notes
This Bolognese sauce is delicious served with spaghetti, tagliatelle, or rigatoni. It also freezes well, so you can make a big batch and save some for later.