MIX all ingredients except chicken and onions; set aside.
PLACE chicken in single layer in parchment paper-lined full-sheet pans (or in lined half-sheet pan for trial recipe). Bake in 325ºF-convection oven 15 min. or until done (165ºF).
BRUSH chicken with barbecue sauce mixture. Bake an additional 5 min. Sprinkle with onions.