My grandmother's recipe for roasted chicken. We are German and she used to do it this way all the time. I never have had a chicken this juicy before; this little trick works and makes the people eating it go silent. It's funny. We nibble on the celery after.
Place chicken in a roasting pan, and season generously inside and out with salt and pepper. Sprinkle inside and out with onion powder. Place 3 tablespoons margarine in the chicken cavity. Arrange dollops of the remaining margarine around the chicken's exterior. Cut the celery into 3 or 4 pieces, and place in the chicken cavity.
Bake chicken uncovered in the preheated oven until no longer pink at the bone and the juices run clear, about 1 hour and 15 minutes. An instant-read thermometer inserted into the thickest part of the thigh, near the bone, should read 180 degrees F (82 degrees C). Remove from heat and baste with melted margarine and drippings. Cover with aluminum foil and allow to rest about 30 minutes before serving.