1Preheat oven to 425 F.
Rinse chicken body cavity; pat dry with paper towels.
Sprinkle inside and out with 1 1/2 teaspoons of salt and the pepper.
2Cut one half of one of the onions into two pieces; place onions pieces and thyme sprigs into body cavity of chicken.
Place chicken, breast side up, on a rack in a shallow roasting pan.
3Cut the remaining 1 1/2 onions into wedges.
Cut the top 1/4 inch of garlic bulbs to expose ends of individual cloves. Leaving garlic bulbs whole, remove any loose, papery outer layers.
4In a large mixing bowl combine onions wedges, garlic bulbs, carrots, mushrooms, celery, chicken broth, oil, bay leaves, sage sprigs, thyme leaves, and the remaining 1 teaspoon of salt.
Mix together well and let sit about two minutes.
5Arrange vegetables around chicken; spoon liquid over chicken.
6Roast uncovered, for 1 1/4 to 1 3/4 hours, or until drumsticks move easitly in sockets and chicken is no longer pink (180 F), stirring vegetables a few times and adding small amounts of additional broth if pan begins to get too brown.
Remove from oven.
7Cover and let stand for 10 minutes before carving chicken.
Remove and discard bay leaves and sage sprigs.
serve chicken with vegetables and pan juices.
8Note: If using skinless chicken, before putting into the oven, bathe the chicken in olive oil and cover with lettuce leaves. The lettuce leaves act like the chickens skin and will help retain the moisture.
The lettuce leaves are easily removed after roasting by simply pouring pan drippings (or juice) over the leaves to reconstitute them.