- 1 small red onion
- 1 pound extra-lean ground beef
- 1 egg
- 1 tablespoon finely chopped fresh parsley
- 2 cloves garlic, minced
- 2 tablespoons Dijon mustard, divided
- 1 large portobello mushroom, stem and gills removed
- 2 tablespoons Kraft Extra Virgin Olive Oil Aged Balsamic Vinaigrette Dressing
- 1 cup Kraft Swiss Au Gratin Shredded Cheese
- 1/4 cup light mayonnaise
- 4 hamburger buns
- Heat barbecue to medium heat.
- Cut onion crosswise in half. Cut half the onion into 1/4-inch-thick slices; finely chop remaining onion. Mix meat, chopped onions, egg, parsley, garlic and 1 tablespoon mustard just until blended; shape into 4 (1/2-inch-thick) patties.
- Brush mushroom and onion slices with dressing. Grill patties and vegetables 6 min., turning vegetables after 3 min. Remove vegetables from barbecue. Turn patties; grill 5 min. (Burgers will not be done.) Meanwhile, cut mushroom into thin slices.
- Top burgers with mushrooms, cheese and onions; grill 3 to 4 min. or until burgers are done (160 degrees F) and cheese is melted. Mix remaining mustard and mayonnaise; spread onto buns. Fill with burgers.