Gather all the ingredients, clean the apple and slice into rings (not too thick) and remove the seeds or any inner part. You can leave the skin on or off.
In a bowl, combine, mayo, mustard, honey, and season with salt. Taste to check and adjust to your preference.
Smear four slices of the bread with the sauce, place a couple of apple slices, then top with turkey breasts and cheese. Use as many apple slices/turkey breasts as you want.
Cover with the other slice bread and spread butter to the outside of each bread slices.
Heat a skillet over medium-low heat and place each sandwich butter side down and toast for about 3 minutes or until the bread is toasted to your desire before you flip it spread butter to the top side and flip to toast the second side.
Remove and continue with the rest of the sandwiches. Allow to rest and slice up.
Serve and enjoy!