Preheat the Oven:
Preheat your oven to 350°F (175°C).
Cook the Noodles:
Cook the egg noodles according to the package instructions until they are al dente. Drain and set aside.
Prepare the Sauce:
In a large mixing bowl, combine the cream of mushroom soup and milk. Mix until smooth.
Add Vegetables and Tuna:
Add the thawed peas, sliced mushrooms, shredded cheddar cheese, and drained tuna to the soup mixture. Season with salt and pepper to taste. Stir to combine.
Combine with Noodles:
Gently fold in the cooked egg noodles, ensuring they are well-coated with the sauce.
Transfer to Casserole Dish:
Transfer the mixture to a greased 9x13-inch baking dish or a similar-sized casserole dish, spreading it evenly.
Prepare Topping:
In a small bowl, combine breadcrumbs with melted butter. Sprinkle this mixture evenly over the casserole.
Bake:
Bake in the preheated oven for approximately 25-30 minutes or until the casserole is hot and bubbly, and the top is golden brown.
Serve:
Allow the casserole to cool for a few minutes before serving. Scoop out generous portions and enjoy the comforting flavors!