Nutrition information is calculated using an ingredient database and should be considered an estimate
Preheat oven to 425°. Line a large baking sheet with shallow sides with foil.
Combine I Can't Believe It's Not Butter! Spread, Dijon, rosemary, garlic, salt and pepper. Gradually stir in balsamic vinegar until blended. Spread 2 tablespoons of mixture over chicken. Toss potatoes and onion (if using) with 2 tablespoons of mixture until evenly coated. Toss broccoli with remaining mixture until evenly coated.
Arrange chicken and vegetables on prepared pan and cook 25 minutes or until chicken is cooked through and vegetables are tender.
Transfer to serving platter and drizzle with any pan juices.