Keeping it Safe
Use a visual test to ensure boneless chicken breasts are thoroughly cooked. Cut small slit in thickest part of chicken piece. If meat is totally white with no pink color, it's safe to eat.
Use Your Broiler
Preheat broiler. Prepare sauce as directed. Place chicken on rack of broiler pan. Broil, 4 to 6 inches from heat, 9 minutes on each side or until cooked through, brushing occasionally with the remaining mustard sauce.