To make onion rings- In a pie plate or shallow bowl combine flour, salt, pepper, and cayenne.
Dredge onion rings in the flour mixture until evenly coated. In another bowl add buttermilk and season it with a little salt and pepper. Dip floured onion rings into the buttermilk and then coat with the flour mixture again. Add oil to a deep pan, just enough to cover the onion rings (or you can use a deep fryer for this).
Heat oil to 360 degrees and fry onion rings in batches until golden brown on both sides (about 4 minutes). Drain on paper towels. Set aside.
Shape ground beef into 6 patties. Season with salt and pepper to your taste. Fry in the pan with a little bit of oil (or on the grill).
Cook until burgers are fully cooked or no longer pink inside. In the last couple minutes of cooking, top each burger with 2 slices of cheese, wait until cheese has melted and removed from the pan.
To assemble burgers – Place a patty on the bottom half of a bun. Top with onion rings; add barbeque sauce and 2 bacon slices to each burger. Add the top half of the bun.