Salt the chicken

• Season the chicken generously with salt all over.
• Let it sit at room temperature.

Make the buttermilk marinade

• Stir the kosher salt into the buttermilk until dissolved.

Marinate the chicken

• Place the chicken in a large resealable plastic bag and pour in the buttermilk.
• Seal the bag, squish the buttermilk all around the chicken and set it on a rimmed plate.
• Refrigerate, turning the bag occasionally if you like.

Bring to room temperature and preheat

• Take the chicken out of the fridge.
• Preheat the oven to 220 °C with a rack in the center position.

Prepare the chicken for roasting

• Remove the chicken from the bag and scrape off as much buttermilk as you can.
• Place the chicken in a cast iron skillet or shallow roasting pan.

Roast the chicken

• Slide the pan to the back of the center rack, legs pointing to the rear left corner and breast toward the center of the oven.
• After about 20 minutes, when the chicken starts to brown, reduce the heat to 205 °C and roast for 10 minutes.
• Turn the pan so the legs face the back right corner and continue roasting until the chicken is brown all over and the juices run clear when a knife is inserted to the bone between leg and thigh.

Rest and carve

• Transfer the chicken to a platter.
• Let it rest before carving and serving.