This is my all time favorite burger. I just love mushrooms, so I double the amount of mushrooms and eat them a long side the burger...lol! If you want an absolutely delicious burger, give this a whirl...I don't think you'll be disappointed...
If baking bacon, bring oven to 400 degree F. Lay slices of bacon on baking sheet, bake until as crisp as you like, turning to bake evenly. Takes about 10 minutes. The bacon stays nice and straight, no shriveling.
Preheat the broiler and line the bottom of a broiler pan with foil.
Lightly mix the beef with 1 1/2 teaspoon salt and 1 teaspoon pepper in a large bowl. ( I sometimes add some onion and garlic powder ).
Gently form into 4 patties, about 3/4 inch thick.
Arrange on the prepared pan and brush both sides with olive oil.
Broil until browned, about 4 minutes per side for medium rare. I broil til well done.
Meanwhile, heat 2 teaspoons olive oil in a large skillet over medium-high heat. Add the onion and cook, stirring, 2 minutes.
Add the mushrooms and cook 2 more minutes.
Add the Worcestershire sauce and cook until the vegetables are tender, about 2 more minutes. Season with salt and pepper and remove from the heat.
You can use whatever favorite condiment you prefer. I used this.
1/4 cup ketchup, 2 teaspoons Dijon mustard, mix set aside.
Top each patty with one-quarter of the mushroom mixture and 1 slice cheese.
Return to the broiler to melt the cheese, about 1 minute.
I then add the bacon, and another slice of cheese, return to broiler for 1 more minute or until cheese is nicely melted.
Spread the buns with the ketchup mixture; sandwich with the patties and some lettuce, and whatever other condiments you prefer.