Combine ham and mayonnaise, mix well.
Spread ham mixture over 4 slices of bread, stack 2 spread slices on top of each other.
Top each sandwich with remaining slice of bread, cut each sandwich in half.
Combine cheese and butter, mix until well blended.
Frost top and sides of each sandwich with cheese mixture, refrigerate several hours.
Place a wire rack on a baking sheet, place ham loaves on rack.
Bake at 450Â° for 2 minutes or until cheese melts.