Rub combined salt and pepper all over chicken, including the stomach cavity. Truss up the chicken neatly.
Combine spice (A) in a small bowl. Stir and mix evenly, then spread mixture over the chicken skin. Leave to marinate for at least an hour.
Scatter combined spice (B) around the roasting pan. Place a rack over the roasting pan and sit the chicken on the rack. Spoon melted butter over chicken. Roast the chicken, breastside down, in a preheated oven at 180°C-190°C for 50-60 minutes. Halfway through, remove the pan and brush chicken with extra melted butter, then turn the chicken over (breastside up). Continue to roast until chicken is cooked through.