Preheat the oven to 375 degrees and lightly grease an 8x8 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 set aside.
In a large mixing bowl, stir together the cream of mushroom soup, milk, drained tuna, frozen peas, half of the shredded cheddar, and a pinch each of salt and pepper.
Add the drained noodles to the bowl and gently fold everything until the noodles are evenly coated.
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 and remaining cheddar cheese. Sprinkle this mixture evenly over the top of the casserole.
Bake for 20 to 25 minutes until the sauce is bubbling and the topping turns lightly golden. Let it rest for 5 minutes before serving.