Preheat oven to 400 degrees.
Prepare a rimmed baking sheet with tinfoil lightly coated with cooking spray.
Using a sharp knife cut slits into the chicken breasts, about ½-1 inch apart and ¾ of the way through the chicken. The depth of the cuts don't have to be exact, just do not cut all the way through the chicken. You will have between 5 and 8 cuts per chicken breast.
Whisk together the onion powder, garlic powder, salt, pepper, and mayonnaise or olive oil.
Brush the bottoms of the chicken breasts with half of the mayonnaise or olive oil mixture. Turn each chicken breast over and place on the baking sheet.
Brush the tops of the chicken with the remaining mayonnaise mixture.
Shove the shaved or sliced ham into each slit and add the cheese on top of the ham.
Sprinkle parmesan cheese, and a light dusting of paprika.
Bake uncovered in the preheated oven for 30 minutes, or until the chicken is cooked through.
Enjoy!