To make the cranberry spread, blend together the mayonnaise, mustard, honey, and dried cranberries and set aside.
Place the pancetta in a pan or on a flat grill heated to medium. Cook until brown and starting to crisp. Drain. Wipe off pan or grill.
Melt 2 teaspoons of butter in medium heated pan or on flat grill. Place cut edges face down on butter until slightly toasted; approximately 1 minute. Remove from pan.
Melt another 2 teaspoons of butter on pan or grill and place bottom of croissant in pan, toasted side facing up. Layer 1 slice of cheese, apple slices, pancetta, and another slice of cheese on top of croissant.
Spread the inside of the top piece of croissant with the cranberry spread and place it with spread face down on layered ingredients.
Lower heat and cover the sandwich with a lid or aluminum foil until the cheese starts to melt; carefully watching the underside so as not to burn. Carefully flip the sandwich over and repeat.