Marcella Hazan's Bolognese Sauce

Name: Marcella Hazan's Bolognese Sauce
Prep time: 20 min
Total time: 20 min
Cuisine: Italian
Ingredients: 2 tablespoons vegetable oil; 8 tablespoons (4 oz) unsalted butter, divided; 1 cup chopped onion; 1 1/3 cups chopped celery; 1 1/3 cups chopped carrot; 1 pound ground chuck (I used 1/2 pound chuck and 1/2 pound veal); 1/2 pound ground pork; Kosher salt and freshly ground black pepper; 2 cups whole milk; 1/8 teaspoon freshly grated nutmeg, or a pinch ground nutmeg; 2 cups dry white wine; 3 cups canned imported Italian San Marzano tomatoes, crushed by hand, with their juice; As much pasta as you wish (Marcella prefers tagliatelle), cooked and drained; Freshly grated Parmigiano-Reggiano cheese, at the table