Tuna Casserole

Good and creamy, got it from my bosses wife who got it from her mother-in law.
Ingredients:

• 8 ounces egg noodles
• 1 (10 1/4 ounce) can cream of celery soup
• 1/2 cup mayonnaise
• 3/4 cup evaporated milk
• 1 cup grated cheddar cheese, divided
• 1/2 cup finely chopped celery
• 1/2 small onion, finely chopped
• 4 ounces mushrooms, drained (optional)
• 1 teaspoon black pepper
• 1 (7 ounce) can tuna, with juice

Directions:

1. Cook egg noodles to al dente in boiling salted water; drain well.
2. Preheat oven to 325°F.
3. Mix all ingredients together in a large casserole dish, reserving 1/2 cup of cheese.
4. Sprinkle reserved cheese over the top.
5. Bake for 30 minutes.
6. Serve hot.