Preheat oven to 350°.
Combine Parmesan cheese, 1 tablespoon olive oil, and bread in a small food processor; pulse 10 times or until coarse crumbs measure 1 1/2 cups.
Heat the remaining 1 tablespoon olive oil in a medium Dutch oven over medium heat. Add onion and celery to pan; cook 6 minutes or until tender, stirring occasionally. Stir in 1/4 teaspoon salt. Add mushrooms; cook 5 minutes or until brown, stirring occasionally. Add 1/2 cup Turkey Stock to pan. Combine milk and flour in a small bowl, stirring with a whisk until blended. Add milk mixture to pan, stirring constantly. Gradually add remaining 1 1/2 cups Turkey Stock and 1/2 teaspoon salt; cook 8 minutes or until mixture thickens. Stir in remaining 1/4 teaspoon salt, chopped cooked turkey, peas, chopped fresh thyme, and freshly ground black pepper; cook 2 minutes or until thoroughly heated.
Spoon the turkey mixture into a 13 x 9-inch baking dish coated with cooking spray. Sprinkle breadcrumb mixture evenly over top of turkey mixture. Bake at 350° for 25 minutes or until filling is bubbly.