Remove any excess fat from the chicken thighs. To marinate add cleaned chicken thighs to a bowl. Season with onion powder, garlic powder, salt, paprika, buttermilk, hot sauce and creole seasoning. Cover and marinate for at least 4 hours. Remove chicken 30 minutes before frying to bring it to room temperature.
In a separate bowl, combine flour, cornstarch, onion powder, garlic powder, paprika, salt, pepper, all purpose seasoning, creole seasoning and cayenne pepper, if desired. Mix well.
Dredge chicken thighs in the seasoned flour one at a time, until well coated. Shake off the excess flour and let it rest until you coat the second piece of chicken.
Add oil to a large skillet over medium-high heat (350 degrees). Fry 2 pieces of chicken at a time. Cook 6-8 minutes on each side. Once cooked, carefully remove the chicken from the oil and rest on a wired rack. Internal temp should be 165 degrees F.
Bring the temperature back up to 350 degrees before frying the next batch. Repeat steps until all the chicken is fried.
Immediately add slices of pepper jack cheese to each chicken thigh. Add to the broiler for about 2 minutes, until the cheese is melted and bubbly.