Preheat the oven to 400°F. Spray a 9"x13" casserole dish with cooking spray and set aside.
Slice each chicken breast in half lengthwise and pound each to an even ½" thickness.
Use the ½ tsp sea salt and ¼ tsp of the black pepper to sprinkle on the top and bottom of each chicken filet.
Lay the filets in the greased casserole dish. Top each filet first with one slice of Swiss cheese and then two slices of folded ham.
In a separate bowl, mix together the mayonnaise, Dijon mustard, and remaining ¼ tsp of black pepper.
Carefully spoon out and spread the mayonnaise mixture on top of the ham on each filet.
Mix together the seasoned panko and parmesan cheese.
Carefully pour the panko mixture on top of the mayonnaise mixture on each chicken filet. Use your fingers to gently press the mixture into the sauce. Spray the top of each with cooking spray to keep it in place.
Bake in the oven for 20-25 minutes or until the middle of the filets reach an internal temperature of 165°F.