Prepare your coals or campfire.
Add the elbow macaroni, water, butter, and salt to a 4-qt Dutch oven. Cover and place on top of a small bed of coals or embers. Place 10-15 coals on top of the Dutch oven. Cook for about 10 minutes, until the pasta is tender and most (but not all) of the liquid has been absorbed.
Carefully remove the Dutch oven from the campfire and set aside the lid.
Stir in the shredded cheese, mustard, milk, and add bread crumbs. Cover and cook for 10 more minutes- until cheese melts.