The day before: remove any packaging from the chickens and place the uncovered birds on a rack in the refrigerator to dry overnight. (This will allow the skin to crisp easily during roasting.) Preheat the oven to 450ºF. Remove the chickens from the refrigerator at least 30 minutes before roasting (this will temper them, helping them cook quicker and more evenly).
Pat them dry with a kitchen towel and truss them with butcher’s twine: with the cavity of the chicken facing you, place the twine under the neck and draw the legs to the breast; loop the twine around the ends of the legs and tie in a knot. Season the birds liberally with salt and fresh pepper, and place the sprigs of thyme on top.
Place in an oven-safe pan or baking dish. Roast in the oven for 25 to 30 minutes or until the leg meat reaches an internal temperature of 150ºF. Let rest for 15 minutes before serving.