1. Spread half of the mustard over 1 slice of bread; layer Monterey Jack cheese, ham, bacon, tomato slices and Cheddar cheese over top. Spread remaining mustard over remaining bread slice. Lightly spread butter over outside of sandwich.
2. Heat skillet over medium-low heat; cook sandwich, pressing lightly, for 2 to 3 minutes per side or until bread is golden brown and cheese is melted. To serve, cut in half.
Tip: For a spicy kick, add fresh or pickled jalapeño slices to the sandwich.