Preheat the oven to 375 F. In a small bowl, mix the mayo or yogurt, parmesan cheese, onion, garlic powder, dried parsley, salt, and pepper, until well combined.

Cut the chicken breasts in half if they are too thick and place them in a baking dish that has been sprayed with non-stick cooking spray.

Spoon the mayo mixture on top of each breast until completely covered by it and bake for 35-45 mins or until cooked and brown.