Hollow out cavity in ground beef & get ready for the best stuffing yet

1. Prepare the box of macaroni and cheese according to the package directions.
2. Meanwhile, heat the oven to 350 degrees F.
3. In a large bowl, combine the ground beef, pork, egg and breadcrumbs. Mix until everything is well-combined.
4. Divide the meat mixture into two large portions. Shape one of the portions into an 8-by-4 loaf and gently press down in the middle of the rectangle, creating a cavity.
5. Fill the cavity with the prepared mac and cheese (not all of what's in the pan will fit) and top it with the cheddar cheese.
6. Use the remaining portion of meat to close the loaf, pinching the sides closed.
7. Bake the meatloaf for 25 minutes.
8. Meanwhile, in a small bowl, whisk together the ketchup, brown sugar and mustard.
9. Brush the ketchup mixture over the meatloaf and bake for an additional 10 minutes, until the mixture reaches 165 degrees F on an instant read thermometer.
Let the meatloaf stand for 10 minutes before slicing.