With the rack in the bottom position, preheat the oven to 200°C (400°F).
In a bowl, combine all the ingredients. Set aside.
Rub the chicken with the butter and mustard. Sprinkle with the dry rub.
Place the chicken on a rack in a roasting pan.
Roast for 15 minutes. Reduce the oven temperature to 180°C (350°F) and continue roasting until a meat thermometer inserted in the thigh without touching the bone reads 82°C (180°F), about 75 minutes. During the last stage of roasting, cover the chicken with aluminum foil if necessary to prevent scorching.