Preheat oven to 325 F. Spray a sheet pan or 9x13 baking dish with cooking spray.
Slice sheet of Hawaiian rolls in half, leaving individual rolls intact. Place bottom on prepared sheet.
In a medium bowl, toss shredded chicken with half of the barbecue sauce. Spread chicken across the bottom of the rolls and brush with remaining barbecue sauce. Sprinkle shredded cheese in an even layer of the chicken, followed by a layer of sliced red onions, and a sprinkle of chopped herbs. Place top of rolls on top.
In a small bowl, mix together melted butter and garlic powder. Brush the rolls.
Loosely tent with aluminum foil and bake for 15-20 minutes until golden brown and cheese is melted.