Making Mac and Cheese Meatloaf Casserole is an easy process if you follow these clear steps:

1. Preheat Oven: Heat your oven to 350°F (175°C).
2. Cook Macaroni: In a large pot, cook the elbow macaroni according to package instructions until al dente. Drain and set aside.
3. Prepare Meatloaf Mixture: In a large mixing bowl, combine the ground beef, chopped onion, breadcrumbs, egg, Worcestershire sauce, garlic powder, onion powder, salt, and pepper. Mix until well combined.
4. Incorporate Cheese and Milk: Add ½ cup of shredded cheddar cheese and milk to the meatloaf mixture. Mix thoroughly.
5. Combine with Macaroni: Gently fold the cooked macaroni into the meatloaf mixture until evenly combined.
6. Layering: If using marinara sauce, spread a thin layer at the bottom of a greased casserole dish. Pour in half of the meatloaf macaroni mixture, spreading it evenly.
7. Top with Remaining Cheese: Sprinkle the remaining cheddar cheese on top of the first layer.
8. Add the Second Layer: Pour the rest of the mixture over the cheese, spreading it out evenly.
9. Bake: Cover the casserole dish with foil and bake for 35 minutes. Remove the foil and bake for an additional 25 minutes, or until the center is cooked through and the top is slightly browned.
10. Serve: Allow the casserole to cool for about 10 minutes before slicing to serve.

Following these steps will lead you to create an unforgettable Mac and Cheese Meatloaf Casserole that is sure to impress everyone at your table.