Preheat the oven to 425ºF and line a baking sheet with a baking rack. Lay out the chicken and pat each piece dry with a piece of paper towel.
In a large bowl, combine the flour, cornstarch, cayenne pepper, paprika, garlic powder, onion powder, kosher salt, and black pepper and stir well. Add the chicken pieces into the bowl and toss to coat each piece. Set aside.
In a smaller bowl, whisk the egg with the buttermilk and hot sauce and, in a shallow dish, scatter the crushed cornflakes.
Remove the chicken from the flour mixture one piece at a time and tap off any excess flour. Dunk and thoroughly coat the chicken in the buttermilk mixture, allow excess to drip off, then roll in the cornflake crumbs. Place the chicken onto the rack-lined baking sheet and continue until all of the chicken is coated, making sure to leave space between each piece.
Bake the chicken in the preheated oven for 15 minutes then reduce the temperature on the oven to 375ºF and continue to cook for another 30 to 35 minutes or until the internal temperature of the chicken pieces reaches 165ºF and the coating is golden brown.
Immediately season the chicken with a pinch of kosher salt and allow it to rest for about 5 minutes before digging in!