In a small bowl, stir together special sauce ingredients. (Adjust amounts to your own personal taste.) Cover and set aside, or chill if not using right away.
Into a medium bowl, grate cheeses, and toss them together to mix evenly. Prep any other ingredients you would like on your burger to have them ready.
Form ground beef (1/4 lb. - 1/2 lb.) into a patty, season both sides with salt and pepper to taste, and grill or fry to desired doneness. When almost done, slather with your favorite barbecue sauce. (*I used Sweet Baby Ray's Original BBQ Sauce.) Cover and set aside to keep warm.
On a flat, non-stick griddle pan, melt butter. Place cheese onto pan over medium-low heat, spreading out into a large circle, but not too thin. Add a little water around the cheese and place a dome lid over to cover. When cheese is lightly browned on the bottom and fully melted, remove from heat. *This only takes a few minutes, so keep checking so that it doesn't burn.
Place lettuce and burger onto a toasted bun bottom. Carefully life cheese skirt from the griddle pan and place on top. Top with bacon slices, onion, and lots of special sauce. Place on top bun and dig in! Enjoy!