Preheat the oven to 350°F and spray your dish with non-stick cooking spray.
In a large bowl mix together the cooked egg noodles, frozen peas, tuna, mushroom soup, 1¼ cups mozzarella cheese, celery salt, pepper, and parsley.
Put tuna mixture in a 9×13 casserole dish.
Bake for 20 minutes, until hot and bubbly.
While the casserole is baking mix together bread crumbs and melted butter.
After 20 minutes, remove the casserole from the oven and top with breadcrumbs and remaining ¼ cup mozzarella cheese.
Return to the oven and bake another 5 to 10 minutes, until bread crumbs had started to brown and the cheese is melted.
Serve warm.