Combine the paprika, black pepper, salt, garlic powder, parsley, and thyme in a small bowl with olive oil. Mix well
Rub the chicken in side and out with the spice mixture, and set into the roasting pan. Place the celery and quartered onions into the cavity of the chicken.
Cover, and bake the chicken in the preheated oven until no longer pink at the bone and the juices run clear, 4 to 5 hours. An instant-read thermometer inserted into the thickest part of the thigh, near the bone should read 180- degrees. Remove the chicken from the pan, cover with a doubled sheet of aluminum foil, and allow to rest in a warm area for 10 minutes before serving.
If I have the time or think about it, I marinate the chicken in the spice mixture mixed with olive oil overnight in the refrigerator.
I have also substituted lemon juice for the olive oil and added a cut lemon to the cavity of the chicken before roasting that is a tasty and lower fat way to prepare this chicken.