Pour buttermilk into a shallow dish. Add pork, flip to coat and submerge. Refrigerate, covered, for at least 2 hours or overnight.
Preheat oven to 425°F. Line baking sheet with foil, set a baking rack on it, and spray lightly with cooking spray.
In a large shallow bowl, mix panko, Parmesan cheese, parsley, mustard powder, salt and pepper. Remove pork from marinade, allowing excess marinade to drip off. Dredge each pork chop in breading mixture, patting lightly so breading adheres. Place on prepared rack.
Bake for 30 to 35 minutes or until internal temperature reaches 145°F.
Allow to rest 5 to 10 minutes before serving. Internal temperature will continue to rise slightly.
Don't have a baking rack? Bake pork chops in baking pan without a rack. They may be slightly less crispy on the bottom side but will still be delicious.