Preheat the oven to 350°F
Cook 8 ounces of egg noodles according to package directions
Drain the noodles and set aside
In a large bowl, mix 2 cans of drained tuna, 1 can of cream of mushroom soup, 1 cup of milk, 1 cup of frozen peas, 1 cup of shredded cheddar cheese, 1/2 cup of chopped onion, and 1/2 teaspoon of black pepper
Stir in the cooked noodles
Transfer the mixture to a greased 9×13-inch baking dish
Top with 1 cup of crushed potato chips or breadcrumbs
Bake for 25 to 30 minutes
Let it rest for 5 minutes before serving