Delicious Grilled Burgers

In a medium bowl, combine beef, onion, garlic salt and pepper. Mix well.

Shape into 6 patties.

In a small bowl, combine cheese, mushrooms, bacon and mayonnaise; refrigerate.

Grill burgers over medium-hot coals turning once.

During the last 3 minutes, spoon 1/4 cup of cheese mixture onto each burger.

Serve on buns with lettuce and tomato.