In a Dutch oven, heat olive oil and unsalted butter over medium heat. Add pancetta and cook until crispy, about 5 minutes. Stir in onion, carrots, celery, and garlic, sautéing until softened, about 7-8 minutes. Add ground sirloin and Italian sausage, cooking until browned, around 5 minutes. Mix in tomato paste, then pour in red wine, milk, and crushed tomatoes. Toss in bay leaves and parmesan rind. Simmer on low heat for 2.5 to 3 hours until thick, stirring occasionally.

Bring a large pot of salted water to a rolling boil. Add lasagna noodles and cook until al dente, approximately 4 minutes. Drain and spread them onto a baking sheet drizzled with olive oil to prevent sticking.

In a saucepan, melt unsalted butter over medium heat. Whisk in flour, cooking for 2-3 minutes until it forms a roux. Gradually add warmed milk, whisking continuously until thickened, about 8-10 minutes. Season with salt, pepper, and nutmeg.

In a greased baking dish, spread a thin layer of béchamel sauce on the bottom. Layer noodles, followed by Bolognese sauce, and sprinkle with parmesan and mozzarella. Repeat layers until all ingredients are used, ending with béchamel and topping with mozzarella and remaining parmesan.

Preheat oven to 375ºF. Cover baking dish with foil and bake for 1 hour, then uncover and bake an additional 15 minutes until golden. Let rest for 20-30 minutes before slicing.