Preheat the oven to 375°F and lightly grease an 8x8 inch baking dish. Bring a large pot of salted water to a boil and cook the egg noodles until just tender. Drain and set aside.
In a large mixing bowl, stir together the cream of mushroom soup, milk, drained tuna, frozen peas, shredded cheddar cheese, salt, and black pepper until evenly combined.
Add the drained noodles to the bowl and gently fold everything together so the noodles are coated in the sauce.
Transfer the mixture to the prepared baking dish and spread it into an even layer.
In a small bowl, mix the breadcrumbs with the melted butter until the crumbs are coated. Sprinkle this mixture evenly over the top of the casserole.
Bake for 25 to 30 minutes until the sauce bubbles around the edges and the breadcrumb crust turns golden.