In a large bowl, whisk together the buttermilk and hot sauce. Add the chicken pieces, ensuring they are completely submerged. Cover and refrigerate for at least 4 hours (or overnight for best results).
In a wide baking dish, whisk together the flour, cornstarch, salt, pepper, paprika, garlic powder, and onion powder until evenly combined.
Remove the chicken from the buttermilk one piece at a time, letting the excess liquid drip off. Press the chicken firmly into the seasoned flour mixture until heavily coated on all sides.
Set the breaded chicken aside on a wire cooling rack for 15 minutes to let the crust hydrate and set.
Fill a large cast iron skillet or Dutch oven halfway with peanut oil. Heat the oil to 350°F (175°C).
Using tongs, carefully drop the chicken pieces into the hot oil without overcrowding the pan. Fry for 12-15 minutes per side until deeply golden brown.
Use a meat thermometer to ensure the internal temperature reaches 165°F (74°C).
Remove the chicken from the oil and drain on a clean wire rack. Serve hot.