Set the oven's temperature to 400°F and use parchment paper to line a baking dish or sheet pan.
Combine the galic powder, onion powder, salt, and black pepper in a small bowl and whisk until well blended.
Apply the seasoning mixture to both sides of the chicken. Sprinkle in the baking dish that has been prepared in a uniform layer.
In a bowl, mix together the mayonnaise, garlic powder, ½ cup Parmesan, salt, and pepper. until thoroughly mixed.
Using a knife, cut the chicken breasts in half horizontally, creating four thinner cutlets through the chicken's thickness. Cover each chicken breast with a layer of mayonnaise.
If desired, sprinkle more parmesan cheese over top.
The top of the chicken should be well browned after 20 to 25 minutes of baking at 400°. or until 165° is reached on a meat thermometer.
Before serving, sprinkle with the parsley.