Line a cookie sheet with parchment, or wax paper and set aside.
Heat the grill to medium-low heat.
To prepare the hamburgers, place the ground hamburger, bacon pieces, cheese bits, A.1. Sauce, garlic, egg, bread crumbs, salt, and black pepper in a large bowl. Mix using your hands until all ingredients are well combined.
Form meat into patties, and place on the cookie sheet, to go to the grill.
While the burgers are cooking on the grill, pour the olive oil into a pan on the stove, and heat to medium. When the pan is hot, add the garlic until gragrant about 2 minutes.
To prepare the mushrooms, first wipe any dirt off mushrooms using a dry paper towel. Decap and slice up mushrooms, add to the pan, and cook until tender.
Stir in sliced green onions, stir remove from heat, and set aside.
When hamburgers are just about done, add a slice of swiss cheese on top of each patty, and close the grill lid until cheese melts, about 2 minutes.
Place patties with cheese on a hamburger bun, top with a heaping spoonful of mushrooms.
Top with additional green onions and serve hot!