Fry bacon on medium heat in a 12 inch Lodge cast iron skillet. Remove when crispy but keep bacon drippings in skillet. Add more bacon drippings or cooking oil, if necessary, to have 1/2 inch depth covering bottom of the skillet.
Add sliced onions to skillet. Cook for 10 to 15 minutes on medium heat until soft and caramelized.
Add peach preserves and apple cider vinegar. Stir well.
Stir in BBQ chicken and all but one tablespoon of chopped parsley. Heat thoroughly until mixture bubbles.
Place cornbread, egg, buttermilk and remaining parsley into a mixing bowl and stir until cornmeal is wet. Crumble in bacon. Stir well.
Pour over top of chicken mixture and spread to cover.
Sprinkle cheddar cheese on top.
Bake in a preheated 425 degree oven for 20 minutes or until cheese melts and cornbread is golden brown and firm to the touch.
Serve immediately.