Place the chicken in a large ziptop bag with the buttermilk and hot sauce. Close the bag, turn until the chicken pieces are fully coated, and refrigerate for at least 2 hours or overnight.
Position a rack in the center of the oven. Preheat the oven to 400 degrees F. Coat a wire rack with nonstick spray and place it on a large rimmed baking sheet.
Set up your dredging station: Place the flour on a wide, shallow plate. Set a medium bowl beside it (this will be for the buttermilk). In a separate, wide bowl (a pie dish works well), mix the cornflake crumbs, paprika, salt, black pepper, cayenne, garlic powder, onion powder, and poultry seasoning in a shallow bowl until the ingredients are evenly distributed.
Remove the chicken breasts from the bag and place them on a clean plate. Pour the marinade into the medium bowl.
Dredge each breast with the flour until fully coated, shaking off any excess. Then coat the chicken in the marinade, shaking off any excess. Last, dip it in the cornflake mixture, patting it a bit if needed to help the cornflakes adhere.
Arrange the chicken pieces on the prepared wire rack. Bake for 15 minutes. Reduce the oven temperature to 350 degrees F and continue baking until the chicken is cooked through (it should register 155 degrees to 165 degrees F on an instant read thermometer) and crispy, about 15 to 20 minutes more. Let rest 5 minutes, then serve
TO STORE: Refrigerate leftover chicken in an airtight storage container for up to 3 days.
TO REHEAT: Reheat baked fried chicken on a baking sheet in the oven at 350 degrees F until hot.
TO FREEZE: I don't recommend freezing this dish, as the cornflake mixture will become soggy once thawed.
*Nutritional information is an estimate and provided as a courtesy. It has been calculated without the buttermilk, as most of the marinade is shaken off.