Assemble burgers in advance and toss em' on the grill when you're ready to eat!
In a medium skillet, melt butter or margarine; add onion and mushrooms. Heat until coated. Remove from heat; mix in ground beef, salt, pepper, garlic, cheese and black olives. Place buns on a double sheet of heavy duty foil. Evenly divide meat mixture into 8 patties and place on bun halves. Place burgers on grill over medium coals and close hood. Grill without turning over for approximately 20 to 25 minutes or until desired doneness.
Assemble these burgers in advance and grill just before serving. Place hickory chips, that have been soaked in water at least 1/2 hour, on coals just before cooking for an appetizing smoky flavor.