"these open-faced burgers turn a meal into a knife-and-fork adventure. Look for texas toast, sometimes labeled "barbecue bread", on the bread isle"

• cooking spray
• 2 cups vertically sliced onions
• 2 tsp. sugar
• 3/4 tsp. salt, divided
• 1/2 tsp. freshly ground black pepper, divided
• 1 (8-ounce) package presliced mushrooms
• 2 tbsp. worcestershire sauce
• 1 pound ground round
• 4 (2-ounce) slices texas toast
• 1/2 cup (2 ounces) shredded swiss cheese
  

• Prepare grill
• heat a medium nonstick skillet over medium heat
• coat pan with cooking spry
• add sliced onion; cover and cook 5 minutes, stirring occasionally
• add sugar, 1/4 tsp. salt, and 1/4 tsp. pepper; cook, uncovered, 5 minutes or until tender, stirring frequently
• remove onion from pan; keep warm
• heat pan coated with cooking spray over medium-high heat. add mushrooms and 1/4 tsp. salt; sauté 5 minutes or until tender
• combine 1/4 tsp. salt, 1/4 tsp. pepper, worcestershire sauce, and beef.
• divide mixture into 4 equal portions, shaping each into a 1/2-inch thick patty
• preheat broiler
• place patties on a grill rack coated with cooking spray; grill 5 minutes on each side or until done
• place bread on grill rack; grill 1 minute on each side or until toasted
• arrange bread on a baking sheet
• top each bread slice with 1 patty, 1/4 cup onion, 1/4 cup mushrooms, and 2 tbsp. cheese; broil 2 minutes or until cheese melts.