Heat oven to 450°F. Spray 13x9-inch (3-quart) baking dish with nonstick cooking spray.
In medium saucepan, bring water to a boil. Stir in stuffing mix. Remove from heat; cover and let stand 5 minutes.
Meanwhile, in large nonstick skillet, cook turkey over medium-high heat until no longer pink. Add peas and carrots, soup, sour cream, mushrooms and milk; mix well. Heat until bubbly.
Spoon 2/3 of stuffing evenly into sprayed dish. Top with turkey mixture and remaining 1/3 of stuffing. Bake 10 to 15 minutes or until bubbly and browned. Let stand 5 minutes before serving.