lasagna Bolognese recipe

2 ounces diced pancetta, finely chopped 1 medium Spanish onion or yellow onion, finely chopped 1 rib celery, finely chopped 1 carrot, finely chopped 4 tablespoons unsalted butter 11 ounces ground beef 4 ounces ground pork 4 ounces ground Italian sausage 1 clove, freshly ground Dash freshly ground cinnamon 1 teaspoon freshly ground black pepper 2 pounds tomatoes , peeled and chopped, or 1 (28-ounce) can whole peeled tomatoes 1 cup whole milk 1/2 teaspoon sea salt Béchamel Sauce: 2 cups whole milk 1/4 cup unsalted butter 1/4 cup all-purpose flour Lasagna: