In a small bowl, thoroughly combine all the spices. Remove giblets from chicken, clean the cavity well and pat dry with paper towels. Rub the spice mixture into the chicken, both inside and out, making sure it is evenly distributed and down deep into the skin. Place in a resealable plastic bag, seal and refrigerate overnight.
When ready to roast chicken, stuff cavity with onions, and place in a shallow baking pan. Roast, uncovered, at 250 degrees for 5 hours (yes, 250 degrees for 5 hours). After the first hour, baste chicken occasionally (every half hour or so) with pan juices. The pan juices will start to caramelize on the bottom of pan and the chicken will turn golden brown. If the chicken contains a pop-up thermometer, ignore it. Let chicken rest about 10 minutes before carving.
To Freeze.. This can be frozen with just the spice rub on before cooking, but I prefer to make several of these and cook them completely and freeze fully cooked. Simply bag and freeze. Warm in the microwave before serving.
Notes : This recipe is a great way to roast a large chicken for planned leftovers. It is reminiscent of those rotisserie style chickens that are so popular now, and it is very easy to make. The meat comes out very moist and flavorful, so it is as good leftover as freshly cooked. Please try it and you will never roast chicken any other way. You need to start this the night before serving.