Heat oven to 350 Spray a 9 x 13" casserole dish w/ cooking spray. Place turkey and stuffing in blender, blend until combined.
Place turkey mix in lg bowl. Add cream cheese, parmesan cheese, mayonnaise and 2 cups mozzarella cheese. Mix w/ mixer on medium until well blended.
Spread 1/2 cup gravy into bottom of casserole dish. Stuff shells w/ turkey mix. Place shells in dish over gravy. Top w/ remaining gravy and mozzarella cheese. bake, covered 45 min. Uncover, bake 10 min, or until browned & bubbly.