This recipe, adapted from Samin Nosrat's "Salt Fat Acid Heat," is inspired by the Southern grandma method of marinating chicken overnight in buttermilk before frying it. You're roasting here, but the buttermilk and salt still work like a brine, tenderizing the meat on multiple levels to yield an unbelievably juicy chicken. As an added bonus, the sugars in the buttermilk will caramelize, contributing to an exquisitely browned skin. Be sure to leave 24 hours for marinating the chicken. While…