In a large bowl, combine chicken, buttermilk, salt, and black pepper.
Cover and marinate for at least 4 hours or overnight in the refrigerator.Always follow proper food safety while handling raw chicken, based on the FDA safe food handling guidelines for poultry. In another bowl, mix flour, cornstarch, and all seasoning spices.
Remove the chicken from the marinade and let the excess drip off.
Coat each piece thoroughly in the flour mixture. Press the coating firmly.
Heat oil to 325°F–350°F (163°C–175°C).
Fry chicken in small batches for 12–15 minutes or until golden brown and fully cooked.The safe internal temperature for chicken should reach 165°F (74°C) according to the USDA-recommended safe internal temperature for cooked chicken. Remove and drain on a wire rack or paper towels.
Rest for 5–10 minutes before serving.