Make-Ahead Turkey Gravy with Porcini Mushrooms and Marsala Wine

INGREDIENTS

• For the turkey neck stock:
• 2 teaspoons vegetable oil
• 4 turkey necks
• 1 onion, chopped
• 1 stalk celery, chopped
• 1 carrot, chopped
• 1/3 cup Marsala wine
• 2 quarts cold water
• 1 bay leaf
• 2 garlic cloves
• 1/4 ounce dried porcini mushrooms
• For the sauce:
• 1 cup hot water
• 1/4 cup butter
• 3 tablespoons all-purpose flour
• 2 tablespoons heavy cream
• salt and ground black pepper to taste