Heat oven to 400° F.
Arrange the onions in a metal roasting pan. Place the chickens on top and tuck the wings under the bodies.
In a small bowl, combine the marmalade, oil, coriander, 2 teaspoons salt, and 3/4 teaspoon pepper. Spread the mixture over the chickens and roast until they are cooked through, about 1 hour, 15 minutes (internal temperature 165° F).
Transfer the chickens and onions to a platter and let rest for 10 minutes.
Strain the pan drippings into a bowl. Let stand for 5 minutes. Skim the fat from the surface and discard.
Serve the chickens and onions with the remaining juices.
Stress-Less Tip: Using two medium chickens instead of one large one cuts roasting time by at least an hour and 15 minutes. Marmalade makes a quick and easy French-style orange glaze.