Serves 6

     1/2 cup butter, divided
     1 (8 ounce) package uncooked medium egg noodles
     1/2 medium onion, finely chopped
     1 stalk celery, finely chopped
     1 clove 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

Preparing

First preheat oven to 375 degrees F / 190 degrees C. With 1 tablespoon butter, basting  the medium baking dish.

Cooking Noodle

Boil a large pot of lightly salted water. Add egg noodles, cook for 8 to 10 minutes, until tender, and drain.

Stir-fry Mushrooms

Melt 1 tablespoon butter in a skillet over medium-low heat. Stir in the onion, celery, and garlic, and cook 5 minutes, until 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.

Making Sauce

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. Stir in tuna, peas, mushroom mixture, and cooked noodles.

Baking

Transfer the sauce and mixed noodles 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. Bake 25 minutes in the preheated oven, or until bubbly and lightly browned.