Place the chicken pieces in a large bowl and season them with salt, crushed garlic, hot sauce, and Creole seasoning.
Pour some of the buttermilk over the seasoned chicken, transfer the chicken to a gallon-sized ziplock freezer bag, and marinate it in the refrigerator for at least 4 hours (or overnight).
Whisk together the flour, cornstarch, baking powder, paprika, garlic powder, onion powder, herbs, cayenne pepper, white pepper, and salt in a large bowl.
Remove the marinated chicken from the buttermilk and let the excess buttermilk drain back into the bag. Then, dredge it in the flour mixture, shaking off excess flour. You could use a ziplock bag for this process, too.
Double dip the chicken in the remaining buttermilk (add fresh buttermilk as needed), then repeat with the flour mixture, shaking off the excess. Let the chicken rest for 10-15 minutes while heating the oil. That will help the coating to stay on better.
Heat oil in a deep fryer or cast iron skillet to 375℉ (190℃). The temperature will drop once you add chicken.
Slowly and carefully place the chicken in the hot oil using tongs. Work in batches to avoid overcrowding the skillet.
Fry the chicken until golden brown, turning once every 10-15 minutes, depending on the thickness of the pieces. Chicken is done when it is no longer pink inside and its juices run clear, or your instant-read thermometer reads 165℉ (75℃). You may do a test by piercing the chicken with a fork.
Drain the chicken on paper towels and then transfer them quickly to a wire rack.
Repeat with the remaining chicken pieces. Let them rest for at least 10 minutes before serving.