Combine coffee rub ingredients and stir to combine. Set aside.
In a large mixing bowl, add the ground beef, salt, pepper, and BBQ Sauce. Mix well by hand, then divide into four equal portions and form into patties.
Rub each burger with the coffee mixture, on all sides.
Heat a large skillet over medium high heat and add the butter. Add the burger patties and cook for 5-6 minutes per side, or until desired doneness. Add a slice of cheese a minute or two before removing from heat.
To assemble burgers: smear both sides of bun with BBQ sauce, then layer the bottom bun with baby greens, followed by the cheeseburger, then add the bacon, 1/4 cup of the caramelized onions, and then the top bun. Serve immediately.