Preheat oven to 400°F. Coat a 1 and 1/2 qt- baking dish with cooking spray. Reserve. Line jelly roll pan with foil. Toss potatoes with oil and thyme, spread in pan. Bake until tender, about 20-25 min.
Coat skillet with cooking spray. Heat over med-high heat. Add turkey, cook until browned. Add veggies. Cook 2 min. Add gravy mix and 3/4 cup water. Cook 5 min. Transfer to baking dish, top with potatoes.
Bake until browned, 15 minutes. Top with cheese. Bake until cheese is melted.