In a large bowl, combine the buttermilk, hot sauce, salt, pepper, paprika, garlic powder, onion powder, and cayenne pepper. Mix well.
Add the chicken pieces to the buttermilk mixture, ensuring they are fully submerged. Cover the bowl and refrigerate for at least 4 hours, or preferably overnight, to achieve juicy meat.
In a separate shallow dish, whisk together the flour and cornstarch. This mixture creates the crispy coating.
Remove the chicken from the marinade, letting excess buttermilk drip off, but do not wipe it dry.
Dredge each piece of chicken thoroughly in the flour mixture, pressing the flour onto the chicken to create a thick, craggy coating. Place the coated chicken on a wire rack.
Pour enough oil into a large, heavy-bottomed pot or deep fryer to reach about 2 inches deep. Heat the oil to 325 degrees Fahrenheit (160 degrees Celsius). Use a thermometer to monitor the temperature.
Carefully place 3 to 4 pieces of chicken into the hot oil, ensuring you do not overcrowd the pot, which lowers the oil temperature.
Fry the chicken for about 6 to 8 minutes per side, turning occasionally, until it is deep golden brown and cooked through (internal temperature should reach 165 degrees Fahrenheit or 74 degrees Celsius). Adjust cooking time based on the size of the pieces.
Remove the chicken from the oil and place it on a clean wire rack set over a baking sheet to drain excess oil. Do not place it on paper towels, as this can steam the crust and make it soggy.
Repeat the frying process with the remaining chicken, maintaining the oil temperature between batches.
Serve the crispy fried chicken hot.
Notes
For extra crispy skin, allow the dredged chicken to rest on the wire rack for 15 minutes before frying. This lets the coating hydrate slightly.
Maintain the oil temperature strictly between 315°F and 330°F for the best texture and to prevent the chicken from absorbing too much oil.
If you are cooking larger pieces like breasts, you may need to finish them in a 350°F oven after frying to ensure they cook completely without burning the exterior.