Best Bacon Hamburgers

This has got to be one of my all time best recipes.
It's a little involved but well worth the effort.
Believe me these are really good, try this one.

Ingredients:
4 slices bacon
1/4 cup chopped onion
6 fresh mushrooms,finely chopped
1 pound lean ground beef
1/4 cup grated Parmesan cheese
1/2 teaspoon pepper
1/4 teaspoon garlic powder
2 tablespoons steak sauce
8 hamburger buns, split and toasted
Leaf lettuce

Directions:
In a large skillet, cook bacon over
medium heat until crisp.
Remove bacon and discard all
but 2 tablespoons drippings.
Saute onions in drippings until tender.
Crumble bacon; add with mushrooms
to skillet and set aside.
Meanwhile, combine beef, cheese, pepper,
garlic powder and steak sauce in a large bowl.
Shape into 1/4 thick hamburger patties.
Divide bacon mixture and place
over eight of the patties.
Place remaining 1/4 patties on top
and press edges tightly to seal.
Grill over medium heat until done.