Preheat oven to 375°.
To prepare chicken, remove and discard giblets and neck from chicken. Rinse chicken with cold water; pat dry. Trim excess fat. Place chicken, breast side up, on a broiler pan coated with cooking spray. Bake at 375° for 1 hour and 20 minutes or until a thermometer inserted into meaty part of thigh registers 175°. Let chicken stand 10 minutes. Discard skin.
To prepare stuffing, cook oats in a large nonstick skillet over medium-high heat 10 minutes or until lightly toasted and fragrant, stirring frequently. Spoon into a medium bowl.
Melt butter in pan over medium-high heat. Add leek and fennel; sauté 8 minutes or until tender. Add leek mixture, broth, and remaining ingredients to toasted oats, and stir well to combine. Spoon mixture into a 1-quart casserole dish coated with cooking spray. Bake at 375° for 20 minutes or until thoroughly heated. Serve with chicken.