Spray 3 1/2- to 4-quart slow cooker with cooking spray. In cooker, mix turkey, onion, carrot, celery, mushrooms, poultry seasoning, salt, pepper and water.
Cover; cook on Low heat setting 5 to 6 hours.
Stir in soup and mixed vegetables. Increase heat setting to High. Cover; cook about 20 minutes or until thoroughly heated.
Meanwhile, heat oven to 450°F. Remove pie crust from pouch; unroll on work surface. With 2 3/4- to 3-inch round cookie cutter, cut 12 rounds from crust, rerolling once; discard scraps. Place pie crust rounds on ungreased cookie sheet. Sprinkle each with about 1 teaspoon Parmesan cheese. Bake about 8 minutes or until pie crust rounds are golden brown and crisp. Immediately remove from cookie sheet to cooling rack.
Top each serving of pot pie with 2 baked crusts.