This classic comfort food brings together tender egg noodles, flaky tuna, and a creamy mushroom sauce topped with golden, crispy breadcrumbs. It's a nostalgic one-dish meal that's perfect for busy weeknights, using simple pantry staples to create a satisfying dinner the whole family will love.
Preheat oven to 375°F (190°C) and grease a 9x13-inch baking dish. Bring a large pot of salted water to a boil and cook egg noodles until al dente according to package directions, then drain.
In a large skillet over medium heat, melt 2 tablespoons butter. Add mushrooms and onion, cooking for 5-7 minutes until softened and mushrooms release their moisture.
Add garlic and cook for 30 seconds until fragrant. Sprinkle flour over the vegetables and stir constantly for 1-2 minutes to create a roux.
Gradually whisk in milk and chicken broth, stirring constantly until the sauce thickens, about 3-5 minutes. Season with salt, pepper, and garlic powder.
Remove from heat and stir in the drained tuna, frozen peas, cooked noodles, and shredded cheese if using. Mix until everything is well combined and evenly coated.
Transfer the mixture to the prepared baking dish and spread evenly. In a small bowl, combine panko breadcrumbs with melted butter and sprinkle over the top of the casserole.
Bake uncovered for 25-30 minutes until the top is golden brown and the casserole is bubbling around the edges. Let rest for 5 minutes before serving, garnished with fresh parsley if desired.
Notes
You can substitute canned cream of mushroom soup (one 10.5 oz can) for the homemade sauce to save time, reducing milk to 1 cup.
Fresh tuna can be used instead of canned - use about 10 oz cooked and flaked tuna.
For extra flavor, add 1 teaspoon of Dijon mustard or lemon juice to the sauce.
Crushed potato chips or French fried onions make a delicious alternative topping to breadcrumbs.
The casserole can be assembled up to 24 hours in advance and refrigerated before baking - add 5-10 minutes to baking time if starting from cold.
Leftovers can be stored in an airtight container in the refrigerator for up to 3 days and reheated in the oven or microwave.
For a lighter version, use reduced-fat milk and skip the cheese, or substitute Greek yogurt for half the milk.
Add vegetables like diced celery, carrots, or bell peppers to the sauté for extra nutrition and color.
The casserole freezes well for up to 2 months - thaw overnight in refrigerator before reheating at 350°F until warmed through.
For individual servings, divide the mixture among 6 ramekins and reduce baking time to 15-20 minutes.