1. Heat oven to 450 degree F. Stuff chicken with 4 of the onion quarters, 4 cloves of the garlic, 2 of the lemon quarters and the rosemary; rub with 1/2 tablespoon of the oil and sprinkle with salt and pepper. Squeeze 1 lemon quarter over chicken.
2. Toss remaining onions, remaining garlic and remaining 1 tablespoon oil in 13x9-inch baking dish. Place chicken, breast side down, over onion mixture. Roast chicken 30 minutes. Turn chicken over; add 1/2 cup of the broth and roast 30 minutes more or until chicken reaches 180 degree F on meat thermometer.
3. Transfer chicken to platter. For gravy, puree onion mixture with remaining 1 cup broth in blender. Pour into saucepan. Stir in 1/8 teaspoon each salt and pepper; squeeze juice from remaining lemon quarter into gravy.
4. Serve chicken with gravy and mashed potatoes. Makes 4 servings.