Prepare the burger patties by mixing together the ground beef with the Worcestershire sauce. Add a little salt and pepper and then press into patties.
Wash and slice the mushrooms.
Slice the onions into half ring strips.
Place the mushrooms and onion slices into a mixing bowl and toss with Marsala cooking wine and some salt and pepper.
Place the mushrooms and onions into the grill basket and grill for 15 to 20 minutes, or until onions turn opaque and mushrooms begin to turn golden/brown.
Grill the burgers alongside the mushrooms.
Prepare the Grilled Garlic Bread.
Cook the spinach as directed on the box.
Serve Grilled Mushroom Burgers with Grilled Garlic Bread and Spinach.