In a medium bowl, lightly mix together the ground beef, salt and pepper. Form into four thick patties. Place on grill or grill pan and cook for four or six minutes. Depending on the thickness of your patty, you might need more or less time.
Top with mushrooms and then cheese, and cook until burgers reach desired level of doneness (about six more minutes for a nice medium-rare burger).
Transfer each burger to the bottom half of a bun -- I like sourdough rolls, but you could also use a traditional burger bun or whole wheat roll. Top each burger with 2 bacon slices and the top half of a bun. Garnish with lettuce, tomato or onion as desired. Serve immediately.
Recipe by In Good Taste at http://ingoodtaste.kitchen/bacon-mushroom-swiss-cheeseburgers/