Cook pasta according to package directions. Drain and set aside.
Meanwhile, preheat oven to 375 degrees F.
Heat a skillet over medium heat and spray with cooking spray. Add celery, onion, and mushrooms and cook until tender.
Stir in condensed soup and evaporated milk. Gently fold in pasta, tuna, and peas.
Transfer mixture to a 1 ½ quart baking dish.
In a small bowl, toss together Parmesan cheese and breadcrumbs.
Sprinkle cheese mixture on top of pasta. Bake for 25-30 minutes, or until heated through and golden brown on top.
Garnish with fresh parsley.