01 - Set oven temperature to 350 degrees Fahrenheit.
02 - Boil egg noodles in a large pot of salted water according to package directions until just tender. Drain and return to the pot.
03 - In a mixing bowl, whisk cream of mushroom soup with milk until evenly blended.
04 - Add drained tuna, frozen peas, and the soup mixture to the noodles. Stir gently until thoroughly combined.
05 - Transfer the mixture to a lightly greased 2-quart casserole dish.
06 - Sprinkle breadcrumbs and shredded cheddar evenly over the top if desired.
07 - Place dish in oven and bake uncovered for 20 minutes or until bubbling and heated through.
08 - Allow casserole to stand for 5 minutes before serving.