Place the chicken in an oven proof dish deep enough to hold the juices. Season the chicken inside and out, add butter to the chicken and stuff the cavity with celery.
Put the chicken in a Preheated oven to 180 celsius / 350 degrees F
A 2kg chicken should be completely cooked in an hour. You’ll know when it’s done when the meat is no longer pink at the bone and the juices run clear.