In a large pot, heat olive oil and unsalted butter over medium heat. Add diced pancetta, sauté until crispy, then remove and set aside.

Using a food processor, finely chop onion, carrots, and celery, then add to the pot. Cook until soft, about 5 minutes, then stir in ground meats.

Cook the meat until fully cooked and stir in tomato paste, cooking until it darkens, then add wine, whole milk, crushed tomatoes, bay leaves, and reserved pancetta. Simmer for 2.5 to 3 hours.

In a large pot of salted water, boil lasagna noodles for about 4 minutes until al dente. Drain and lay them flat on a parchment-lined baking sheet with olive oil.

In a medium saucepan, melt butter over medium heat. Whisk in flour and cook for about 2-3 minutes until golden. Gradually add warmed milk while whisking until thickened, about 5-7 minutes. Stir in Parmesan and nutmeg.

Preheat your oven to 375°F (190°C). In a greased baking dish, layer béchamel, noodles, Bolognese, another béchamel layer, and mozzarella. Repeat until all ingredients are used, finishing with béchamel and mozzarella on top.

Cover with foil and bake for 1 hour, then remove foil and bake for an additional 15 minutes until golden. Rest for 20-30 minutes before serving.