This hearty macaroni casserole is easy to make and very family-friendly. Prepare it the night before and reheat in the oven for a quick, weeknight meal.
Heat oil in skillet and brown the ground beef with the chopped onion. Preheat oven to 425 degrees. Grease or spray oil in an ovenproof casserole dish. Add the cooked macaroni and meat/onion mixture. Whisk together milk and eggs; add about half of the cheese. Pour the mixture over the macaroni and meat in the casserole. Top with the remaining cheese and bake in the preheated oven for 40 minutes, or until the cheese is golden brown and the casserole is heated throughout.