Remove the wingtips by cutting through the first wing joint with poultry shears or a sharp knife. Reserve for stock.
Season the chicken generously with salt and let it sit for 30 minutes.
Stir 2 tablespoons of kosher salt or 4 teaspoons fine sea salt into the buttermilk to dissolve.
Place the chicken in a gallon-size resealable plastic bag and pour in the buttermilk.
Seal the bag, squish the buttermilk around the chicken, place on a rimmed plate, and refrigerate.
Remove the chicken from the fridge an hour before cooking.
Preheat the oven to 425°F (220°C) with a rack set in the center position.
Scrape off as much buttermilk as possible from the chicken.
Tie together the legs of the chicken with a piece of twine.
Place the chicken in a 10-inch cast iron skillet or shallow roasting pan.
Roast the chicken in the oven at 400°F for about 60-70 minutes, rotating and moving the pan for even cooking.
Let the chicken rest for 10 minutes before carving and serving.
