tuna noodle casserole from scratch

this is a pretty tasty one :)
Serves: 5 or 6

Ingredients

• 1/2 cup butter, divided
• 1 (8 ounce) package uncooked medium egg noodles (i used macaroni)
• 1 medium onion,  chopped
• 1 pepper, chopped
• 1 stalk celery, finely chopped
• 2 or 3 cloves garlic, minced
• 8 ounces button mushrooms, sliced
• 1/4 cup all-purpose flour
• 2 cups milk
• salt and pepper to taste
• 2 (6 ounce) cans tuna, drained and flaked
• 1 cup frozen peas, thawed
• 3 tablespoons bread crumbs
• 2 tablespoons butter, melted
• 1 cup shredded Cheddar cheese 
• something spicy (creole seasoning, red pepper, etc)

Directions

1. Preheat oven to 375 degrees F (190 degrees C). Butter a medium baking dish with 1 tablespoon butter.
2. Bring a large pot of lightly salted water to a boil. Add egg noodles, cook for 8 to 10 minutes, until al dente, and drain.
3. Melt 1 tablespoon butter in a skillet over medium-low heat. Stir in the onion, celery, pepper, and garlic, and cook 5 minutes, until theyre tender. Increase heat to medium-high, and mix in mushrooms. Continue to cook and stir 5 minutes, or until most of the liquid has evaporated.
4. Melt 4 tablespoons butter in a medium saucepan, and whisk in flour until smooth. Gradually whisk in milk, and continue cooking 5 minutes, until sauce is smooth and slightly thickened. Season with salt and pepper, and other spices. Stir in tuna, peas, mushroom mixture, and cooked noodles. Transfer to the baking dish. Melt remaining 2 tablespoons butter in a small bowl, mix with bread crumbs, and sprinkle over the casserole. Top with cheese.
5. Bake 25 minutes in the preheated oven, or until bubbly and lightly browned.