Preheat oven to 375℉.
Spray a 13X9 inch oven safe casserole dish with cooking spray. Set aside
Cut each chicken breast into four equal sized pieces.
Place a piece of chicken between a length of plastic wrap and pound meat with a mallet to a ½ inch thickness.
In a mixing bowl combine Parmesan cheese, Ranch seasoning, garlic powder, onion powder, and mayonnaise. Stir until you have a thick paste.
Place crushed Ritz crackers in a shallow bowl.
Spread the seasoned mayonnaise mixture onto each piece of chicken coating each piece entirely.
Roll chicken in the crushed Rita crackers to coat each pice of chicken completely, pressing the chicken into the crumbs so they stick to the chicken.
Place chicken in a single layer in the prepared casserole dish.
Spray chicken lightly with some of the cooking spray.
Bake for 40-45 minutes, uncovered, or until chicken is cooked through and cracker crumbs are golden brown.
Serve hot with your favorite sides.