Every recipe I've looked at calls for breadcrumbs. About 3/4cup per 2lbs. of ground beef. And also an egg to bind it all together. But why are you putting macaroni and cheese inside meatloaf? Why not just make regular meatloaf and have mac & cheese as the side dish?
_________________________
"Returning hate for hate multiplies hate, adding deeper darkness to a night already devoid of stars." - Martin Luther King, Jr.