Preheat oven to 375°F; grease a 9x13-inch dish with butter or cooking spray.

Cook noodles according to package until al dente; drain well and set aside.

Mix soup, milk, tuna, peas, and half the cheddar in a large bowl; season with salt and pepper.

Stir in noodles until combined; pour into prepared dish.

Mix breadcrumbs with melted butter in a small bowl; top casserole with remaining cheese, then buttered crumbs.

Bake 25-30 minutes until bubbly with golden topping; rest 5 minutes before serving.