Scrum � Delicious Burgers

1 1/2 Pounds ground beef
3 Tablespoons onion, finely chopped
1/2 Teaspoon garlic salt
1/2 Teaspoon pepper
1 Cup Cheddar cheese, shredded
1 (4 oz) Can sliced mushrooms
6 Bacon strips, cooked & crumbled
1/4 Cup mayonnaise
6 Hamburger buns, split
Lettuce leaves & tomato slices, optional

In a medium bowl, combine beef, onion, garlic salt, & pepper. Mix well and shape into six patties, 3/4" thick.
In a small bowl, combine the cheese, mushrooms, bacon and mayonnaise, refrigerate.
Grill burgers over medium heat for 10 to 12 minutes or until no longer pink, turning once.
During the last 3 minutes, spoon 1/4 cup of the cheese mixture onto each burger. Serve on buns with lettuce and tomato if desired.