Prep the chicken and veggies – Remove and discard the chicken giblets and parts. Wash the celery and cut off the leaves. Wash the lemon and cut it into four pieces.
Season the chicken – Rub the chicken with butter and then the seasonings (onion powder, garlic powder, and rosemary.) Place celery, lemon pieces and remaining butter inside the chicken cavity.
If desired, cut veg like potatoes and carrots into large chunks and place under the bird if you don't have a rack.
Place the chicken on a roasting pan with a rack. Greasing the rack will help during cleanup.
Bake uncovered for 1 hour and 15 minutes or until it reaches an internal temperature of 165 F degrees. A meat thermometer is the best way to be sure.
Remove the chicken from the oven and baste with drippings.
Loosely cover the chicken with aluminum foil and allow it to rest for 30 minutes.