Tuna Noodle Casserole

My mom's recipe with my personal twist, it's a casserole packed with noodles, cheese, tuna and vegetables.  Makes great leftovers the next day by Kathy and Lacey Johnston.
Serves 4 - 6.

• 1 box Tri-Color Rotini
• 1/2 cup Saltines, crushed or Panko Bread Crumbs
• 1 tbsp Unsalted Butter, melted
• 3 stocks Celery, sliced
• 1/2 Yellow Onion, finely chopped
• 1/4 cup Unsalted Butter
• 1/4 cup All Purpose Flour
• 1/2 tsp Kosher Salt
• 1/2 tsp Dry Mustard
• 1/4 tsp Black Pepper
• 2 cups Milk
• 2 (6 oz.) cans Tuna packed in water, drained
• 1 cup Sharp Cheddar Cheese, cut into 1/2" cubes
• 1/4 cup Roasted Sweet Red Peppers, seeded and chopped (optional)
• 1/4 cup Crimini Mushrooms, chopped (optional)

1. Cook noodles according to package directions, drain and set aside.
2. Preheat oven to 375* degrees F.
3. In large saute pan, saute celery, mushrooms and onion in butter over medium-high heat till tender.
4. Stir in flour, salt, dry mustard and black pepper till flour is disolved.
5. Add milk, cook and stir until slightly thick and bubbly.
6. Remove from heat, add cheese, tuna, red peppers and noodles, stir till combined.
7. Transfer to casserole dish, sprinkle with bread crumbs and then drizzle with melted butter.
8. Bake, uncovered, for 35 minutes or until breadcrumbs are golden.