Heat a large cast iron skillet over medium heat. Add the butter to the skillet and melt.

Place one tortilla in the skillet and top with half of the cheese.

Add the chopped meatloaf pieces and top with the remaining cheese and second tortilla.

Cook for 2 minutes or until the tortilla is golden brown and the cheese is melting.

Flip carefully and continue cooking until the bottom tortilla is golden brown and the meatloaf is heated through.  Cut into four pieces.

While the quesadilla is cooking, whisk together the ketchup, mustard, and brown sugar to make the dipping sauce. Serve alongside the quesadilla.