Preheat oven to 180 C / Gas 4. Pour the chicken stock into a small roasting tin and set aside.
Loosen the skin from the breasts and thighs of the chicken. Stuff the butter pieces evenly underneath the skin of the chicken and place into the roasting tin. Squeeze the orange halves over the chicken and stuff the orange halves into the chicken cavity. Tie the legs together with kitchen twine. Sprinkle the chicken with salt and pepper to taste, then rub in the garlic. Drizzle the melted butter all over the chicken, then lay the herb sprigs onto the breast and around the legs.
Cover the dish with foil and bake in the preheated oven for 20 minutes. Uncover and baste the chicken with the juices. Continue cooking until the chicken is no longer pink or until an instant-read thermometer inserted into the thickest part of the thigh reads 74 degrees C, 1 to 2 hours. Baste the chicken every 10 to 15 minutes after you uncover it. Once cooked, allow the chicken to rest out of the oven for 10 minutes before slicing.