Preheat oven to 350 degrees
Rinse and dry the chicken.
Combine the bacon fat and butter and rub this mixture over the entire chicken.
Sprinkle the entire chicken with the salt, pepper and poultry seasoning, including the inside cavity of the chicken.
Mix together the onion, orange, celery and brown sugar. Remove the leaves from two stems of the rosemary and combine it with the onion mixture. Stuff this mixture into the cavity of the chicken.
Use a small paring knife and cut 1 slit at both ends of each breast, and one slit in the leg and thigh section of the chicken. Gently insert the remaining rosemary springs into the chicken.
Truss the chicken and place it on a rack in a roasting pan. Place in the center of the oven. Roast the chicken for 45 minutes-1 hour, the juices will run clear when the chicken is done. About 15-20 minutes into the roasting of the chicken, baste the skin with the pan drippings.
Allow the chicken to rest for 10 minutes before carving. Gently remove the inserted rosemary sprigs before carving and serving.
Yield: 4-6 servings