Whisk the buttermilk with the garlic powder, onion powder, cayenne and salt. Add the chicken, cover and refrigerate for at least 1 hour or overnight.
Heat the oven to 425 degrees. Set a wire rack on a lined baking sheet.
Mix the cornmeal, flour and all the crust spices in a shallow dish.
Lift each piece of chicken from the buttermilk, let the extra drip off, then press it into the crust on all sides.
Set the chicken on the rack and brush or drizzle with the avocado oil or ghee.
Bake for 40 to 45 minutes, until golden and crisp and the thickest piece reads 165 degrees. Rest 5 minutes before serving.