Cook egg noodles according to package directions, then drain them. In a large bowl, combine the condensed cream of mushroom soup, milk, drained tuna, and frozen peas, stirring until well mixed.

Add the cooked egg noodles to the tuna mixture, along with half of the shredded cheddar cheese, and stir to combine all ingredients evenly.

Pour the mixture into a 9x13 inch baking dish, then sprinkle the remaining cheddar cheese and buttered breadcrumbs over the top; bake in a preheated oven at 375°F (190°C) for 20-25 minutes, or until the casserole is bubbly and the topping is golden brown.