Remove and discard giblets and necks from hens. Rinse hens under cold water; pat dry. Remove skin; trim excess fat. Split hens in half lengthwise. Sprinkle salt and pepper over hen halves; set aside.
Combine mustard and next 5 ingredients (mustard through cloves) in a small bowl; set aside.
Prepare grill or broiler. Place hen halves, meaty sides up, on grill rack or broiler pan coated with cooking spray; cook 15 minutes on each side or until juices run clear, basting occasionally with mustard mixture. Garnish with rosemary sprigs, if desired.