Lasagna Bolognese, Simplified

Ingredients

• 1 medium carrot, peeled and roughly chopped
• 1 medium rib celery, roughly chopped
• 1/2 small onion, roughly chopped
• 1 (28 ounce) can whole tomatoes with juice
• 2 tablespoons unsalted butter
• 8 ounces ground beef, preferably 90 percent lean
• 8 ounces ground pork
• 8 ounces ground veal
• 1 1/2 cups whole milk
• 1 1/2 cups dry white wine
• 2 tablespoons tomato paste
• 1 teaspoon table salt
• 1/4 teaspoon ground black pepper
• 4 tablespoons unsalted butter
• 1/4 cup unbleached all-purpose flour
• 4 cups whole milk
• 3/4 teaspoon table salt
• 15 sheets no-boil lasagna noodles (9 ounces)
• 4 ounces Parmesan cheese, grated (2 cups)