Prep Time: 10 minutes
Cook Time: 10 minutes
Combine meat, 3/4 teaspoon salt and 1/4 teaspoon pepper, mixing lightly but thoroughly. Shape to form 4 patties, 1/2-inch thick.
Grill or broil patties 4 to 5 minutes per side or until internal temperature reaches 160°F.
Meanwhile, cook onion in a large nonstick skillet coated with cooking spray over medium-high heat 2 minutes. Add mushrooms, Worcestershire sauce, remaining 1/4 teaspoon salt and 1/8 teaspoon pepper; cook and stir 5 minutes or until tender.
Place cheese over patties during the last minute of cooking. Serve in rolls topped with mushroom mixture.