Remove the chicken from the fridge 1 hour before cooking.
Preheat the oven to 425°F (220°C) with the rack in the center position.
Take the chicken out of the brine, allowing excess buttermilk to drip off, and tie the legs with butcher’s twine.
Place the chicken in a 10-inch cast-iron skillet or shallow roasting pan, positioning it so the legs point toward the oven’s hottest spots (usually the rear corners).
Roast for 20 minutes until the chicken begins to brown. Lower the oven temperature to 400°F (200°C) and roast for an additional 40 minutes, rotating the pan halfway through.
Use a meat thermometer to check for doneness: the internal temperature should reach 165°F (74°C) at the thickest part of the meat.