Salt the chicken generously inside and out. Let sit for 30 mins.
Add buttermilk and 2 tbsp of kosher salt to a large ziplock bag.
Place the chicken in the bag and seal. Move around so that the buttermilk gets into all parts of the chicken.
Place the bag in the refrigerator for 24 hours.
Remove the chicken from the fridge one hour before you plan to cook.
Preheat the oven to 425°.
Remove the chicken from the bag and using your hands press as much of the buttermilk off of it as you can. Place in a roasting pan.
Put the pan in the back of the oven with the legs pointing to the back left corner.
After 20 minutes, reduce the heat to 400°.
After 10 minutes rotate the pan so the legs are pointing to the back right corner.
Continue cooking for another 30 minutes or until the juices run clear.
Remove from the oven and allow to rest for 10 minutes before carving.