Place chicken pieces in a large bowl and add salt, pepper, garlic powder, dried mustard, paprika, and sage. Stir to coat the chicken evenly.
Pour the buttermilk over the seasoned chicken and mix well. Refrigerate for at least 1 hour and up to overnight.
In a shallow dish, whisk together flour, baking powder, salt, garlic powder, paprika, basil, thyme, onion powder, and cayenne pepper.
Heat the oil in a large, heavy-bottom pan to about 340 degrees Fahrenheit.
Remove each chicken piece from the marinade, place it in the flour mixture, and toss to coat thoroughly.
Fry in batches, cooking 4-5 pieces at a time until golden brown, about 15 minutes. Ensure each piece reaches an internal temperature of 170 degrees Fahrenheit.
Drain the fried chicken on a wire rack.