Prep the chicken 24 hours in advance: cut the first joint of the wings off the chicken and salt generously and leave sitting on the counter for 30 minutes.
Pour buttermilk into a plastic bag and add 2 tbsp salt. Shake thoroughly. Add the chicken to the buttermilk and return to the fridge. Let it marinate for 24 hours or so.
One hour before cooking, pull the chicken out of the fridge to allow it to get to room temperature. Preheat the oven to 425°F, with a skillet inside.
Loosely scrape the excess buttermilk off the chicken skin. When the oven is preheated, pull the skillet out and add the chicken. Position the skillet so the drumsticks face a back corner of the oven.
After 20 minutes, turn the heat down to 400°F. Cook for 10 minutes more, then rotate the legs to face the other back corner.
Cook for 20-30 minutes more, until a meat thermometer reads 165°F. Let rest for 10 minutes before serving.