Preheat the oven to 375 degrees and lightly grease a 9 by 13 inch baking dish.
Bring a large pot of salted water to a boil and cook the egg noodles according to package directions until just tender. Drain and return them to the pot.
Stir the cream of mushroom soup, milk, salt, and pepper into the noodles until evenly combined.
Add the drained tuna, frozen peas, and half of the shredded cheddar cheese. Mix gently so the tuna stays in chunks.
Transfer the mixture to the prepared baking dish and spread it into an even layer.
In a small bowl, toss the panko breadcrumbs with the melted butter until coated. Sprinkle the remaining cheddar cheese over the casserole, then top with the buttered breadcrumbs.
Bake for 25 minutes until the topping is golden and the edges are bubbling. Let it rest for 5 minutes before serving.