For marinade: In a large zip-top bag place chicken pieces with the buttermilk and chipotle. Close bag and mix, making sure mixture is evenly distributed. Marinate for up to 8 hours or overnight in the refrigerator.
Fill a large 12-inch cast-iron skillet with oil to the depth of about 1/2 to 3/4-inch and heat until hot, about 325 degrees F.
In a shallow dish mix the flour and cornmeal with the seasonings. Remove the chicken from the marinade and dredge into the flour/cornmeal mixture. Repeat this process until all pieces are coated. Gently lower the chicken into the hot oil and fry for about 10 minutes on each side, until golden brown and the chicken is cooked through. The oil temperature will drop to about 290 degrees F when the chicken is first added to the hot oil, but will raise back up to 325 degrees F during the cooking process. Use an instant-read thermometer inserted in the thickest part of the chicken pieces, not touching the bone nor piercing through, to make sure it registers 165 degrees F before removing it from the oil. Drain on paper towels and serve.