Cook bacon until crisp. Remove bacon and discard all but 2 tablespoons drippings.

2. Sauté onion in drippings until tender. Crumble bacon: add with mushrooms to skillet and set aside.

Meanwhile, combine beef, pork, cheese, pepper, garlic powder, and steak sauce in a large bowl. Shape into 16 patties. Divide bacon mixture and place over eight of the patties. Place remaining patties on top and press edges tightly to seal. Grill over medium coals until well-done.