Ragù alla Bolognese

INGREDIENTS

• 4 tablespoons unsalted butter
• 4 tablespoons flour
• 2 2/3 cups milk
• Salt and freshly ground pepper to taste
• 3 tablespoons extra virgin olive oil
• 3 ounces pancetta, finely chopped
• 1 medium onion, minced
• 3 medium stalk celery with leaves, minced
• 3 small carrot, minced
• 10 ounces ground pork
• 10 oz ounces ground beef
• 2 ounce thinly sliced Prosciutto, chopped
• 2/3 cup dry red wine
• 1 1/2 cups chicken stock
• 2 cups milk
• 3 cups canned plum tomatoes, drained
• Salt and freshly ground black pepper to taste
• Freshly grated nutmeg to taste