Crush the stuffing mix into crumbs in a bowl; stir garlic powder and onion salt into crumbs.
Place flour in a shallow bowl. Beat egg and milk together in a separate shallow bowl.
Dip turkey cutlets in flour, then in egg mixture; gently press into crumbs to coat.
Place the breaded cutlets into a 9x13-inch baking dish.
Bake in the preheated oven until the juices run clear and the cutlets are no longer pink inside, about 20 minutes.
Whisk dry gravy mix with water in a saucepan until smooth, place over medium heat, and bring to a boil, whisking constantly. Reduce heat and simmer 1 minute.
