1. Preheat oven to 400 degrees F. Cut two large onions into thick slices and put in the center of a roasting pan. Place a cleaned 5-lb. whole chicken, breast-side up, on top of the onions. Brush with 1 Tbs. olive oil and season with 1/4 tsp. salt and 1/4 tsp. ground black pepper. Pour 1 cup low-sodium chicken stock into bottom of the pan. Roast 11/4 to 11/2 hours or until chicken is done. Cover and let rest on a cutting board. Place pan with onion and juices on the stove over medium heat. Stir to break up onion. Add 1/2 cup chicken stock and bring mixture to a boil. Whisk in a mixture of 1/4 cup cold water and 2 Tbs. all-purpose flour. Reduce heat and simmer until thickened and bubbly, stirring occasionally. Simmer 1 minute more. Serve chicken with sauce.