Lasagna Bolognese

Name: Lasagna Bolognese
Ingredients: 1 large onion, coarsely chopped; 1 medium carrot, peeled, coarsely chopped; 1 celery stalk, coarsely chopped; 2 tablespoons olive oil; 1 pound ground beef chuck; 1 pound ground pork; 4 oz. pancetta (Italian bacon), finely chopped; Kosher salt and freshly ground black pepper; 1 cup dry white wine; 1 cup whole milk; 1 14.5-oz. can crushed tomatoes; 3 cups low-sodium chicken broth, divided; ½ teaspoon kosher salt; 3 cups all-purpose flour plus more; 4 large eggs, room temperature; 5 tablespoons unsalted butter; ¼ cup all-purpose flour; 4 cups whole milk, warmed; pinch of freshly ground nutmeg; Kosher salt; Unsalted butter, room temperature (for dish); 2 cups finely grated Parmesan; A pasta maker