Place chicken in a bowl and add buttermilk( depends on how much chicken you are cooking, you want to cover it) hot sauce, salt and pepper, stir to coat and blend spices, cover and place in fridge 3-4 hours
Using a food processor, ( I do them separate) pulse the onion and parmesan until crushed well. Place in a bowl. Then add the panko, garlic powder, parsley flakes, cayenne pepper and paprika, pulse 3 or 4 times, add to the bowl of parm and onions stir to mix together.
remove chicken and coat one piece at a time. Place in baking dish and bake 35-45 minutes at 350 or until chicken reaches 165 degrees. ( I covered mine with foil the last 15 minutes)