Whisk balsamic vinegar with oil, barbecue sauce, maple syrup, mustard, garlic, salt and pepper. Measure 2 tbsp (30 mL) vinaigrette and brush the chicken. Mix peppers with an additional 2 tbsp (30 mL) of vinaigrette.

Preheat grill to medium. Add chicken and grill, turning once, for 15 minutes or until well cooked and an instant-read thermometer registers 165°F (74°C). Meanwhile, add peppers and grill for 12 minutes or until tender. Chop chicken and vegetables finely.

Meanwhile, cook macaroni according to package directions. Mix hot macaroni with chicken, peppers, tomatoes, green onions and remaining vinaigrette until all combined. Sprinkle with cheese (optional). Serve hot.