This corned beef and noodle casserole is a delicious way to use the leftover corned beef, and it's a meal in one dish. Serve this easy corned beef casserole with a tossed salad and cornbread or biscuits for a hearty meal. Though leftover or deli corned beef will have the best flavor and texture, this casserole can be made with canned corned beef as well. When we made it recently to update the photo, we used canned. We added it to the noodle mixture cold, without browning it first.