Season both sides of the chicken with mesquite seasoning and place it in a large baking dish.
Drizzle barbecue sauce over each chicken breast and sprinkle with diced onion.
Bake uncovered for 20 minutes, then remove the dish, add cheese and bacon to the top and return to oven for 5-10 minute or until the cheese is melted and the chicken is done (internal temperature of 165˚F.)
Notes
Source-grounded recipe; use a thermometer for doneness.