In a Dutch oven, heat 1 tablespoon of olive oil and 1 tablespoon of butter over medium heat. Add 6 oz of diced pancetta and cook until crispy, about 5-7 minutes. Remove the pancetta and set aside.

Using a food processor, pulse 1 chopped onion, 2 carrots, 2 celery ribs, and 4 cloves of minced garlic until finely chopped. Cook 1 lb of ground sirloin and 1 lb of ground Italian sausage in the rendered fat on low heat until browned, about 10 minutes. Stir in the minced vegetables and sauté until soft, approximately 5-7 minutes.

Add 6 oz of tomato paste to the meat mixture and cook for 2-3 minutes, allowing it to darken slightly. Pour in 1 ½ cups of medium-bodied red wine, scraping the bottom of the pot to deglaze it.

Let it simmer for about 5 minutes until the wine reduces slightly. Mix in 1 cup of whole milk, 28 oz of high-quality canned crushed tomatoes, and 2 bay leaves. Return the crispy pancetta and stir everything together.

Bring the sauce to a gentle simmer, cover partially with a lid and cook for at least 2.5 to 3 hours, stirring occasionally.

In a saucepan over medium heat, melt 5 tablespoons of unsalted butter. Add ¼ cup of all-purpose flour and whisk continuously for about 1-2 minutes to form a roux. Gradually pour in 4 cups of warmed whole milk, whisking until thickened, about 5-7 minutes. Season with nutmeg, salt, and pepper to taste.

Bring a large pot of salted water to boil. Add 20 sheets of egg lasagna noodles and cook until al dente, about 5-7 minutes. Drain, drizzle with olive oil, and lay flat.

Preheat your oven to 375°F (190°C). Grease a 9x13-inch baking dish. Begin layering: spread béchemel, add noodles, then Bolognese, another layer of béchemel, diced mozzarella, and sprinkle Parmesan. Repeat until components are used, finishing with béchemel and Parmesan.

Cover the lasagna with aluminum foil and bake for 1 hour. Remove foil and bake for an additional 15 minutes until golden. Let rest for 20-30 minutes before serving.