Slice the chicken breasts lengthwise and pat dry with a paper towel. Place them on a piece of plastic wrap and place a second piece over the chicken breasts. Pound them as thin as you can using a meat mallet or rolling pin, without tearing the meat.
Place a slice of ham and 1 ½ slices of Swiss cheese over each breast and roll cigar-style.
Wrap the rolled up chicken breasts in plastic wrap as tight as you can, pinching the excess on the sides as if you are rolling a Tootsie Roll. Refrigerate at least 30 mins and up to a day in advance.
Preheat the oven to 400 F. Remove the chicken breast from the oven and unwrap. Season with salt, pepper, garlic powder, onion powder, and mustard powder.
Roll into the melted butter and the crushed corn flakes until fully breaded.
Bake for 30 minutes or until the internal temperature of the chicken breasts reaches 160F.
Stir the mayo and mustard to make the sauce and serve over the baked chicken breasts.