Prep the chicken: Pound each breast to 3/4 inch even thickness. Pat dry with paper towels.
Set up breading station: Flour in dish one, beaten eggs in dish two, panko and plain breadcrumbs mixed with all seasonings in dish three.
Bread the chicken: Coat in flour, then egg, then press firmly into the breadcrumb mixture. Rest on a wire rack for 5 minutes.
Pan fry: Heat oil in an oven-safe skillet over medium-high. Cook chicken 3 to 4 minutes per side until deep golden brown.
Bake: Transfer skillet to a 400 degree oven. Bake 12 to 15 minutes until internal temperature reaches 165 degrees.
Add toppings: Remove from oven, layer one slice of ham then one slice of Swiss cheese on each breast. Return to oven 2 to 3 minutes until cheese melts.
Make the sauce: Whisk Dijon, yellow mustard, honey, mayonnaise, and vinegar together until smooth. Serve alongside the chicken.