The Most Delicious Lasagna of All Time

Name: The Most Delicious Lasagna of All Time
Prep time: 35 min
Cook time: 1 h 40 min
Total time: 2 h 15 min
Cuisine: European, Italian
Ingredients: 4 ounces diced pancetta (about 1 cup); 1 medium yellow onion, finely diced (about 1 1/2 cups); 1 medium carrot, peeled and finely diced (about 1/2 cup); 1 medium stalk celery, finely diced (about 1/3 cup); 3 cloves garlic, minced; Olive oil, as needed; 1 pound lean ground beef; 1 teaspoon kosher salt, plus more as needed; 1/4 teaspoon freshly ground black pepper; 2 tablespoons tomato paste; 1/2 cup dry white wine; 1 (28-ounce) can crushed tomatoes; 1 (15-ounce) can tomato sauce; 2 cups whole or 2% milk, at room temperature; 4 tablespoons (1/2 stick) unsalted butter; 1/4 cup all-purpose flour; 1 teaspoon kosher salt; 1/8 teaspoon ground nutmeg; 15 dried lasagna noodles (not no-boil; most of a 1-pound box); 2 ounces grated Parmesan cheese (1 1/3 cups freshly grated or 1 cup store-bought grated), divided