Mushroom burger sliders

Name: Mushroom burger sliders
Cuisine: American
Ingredients: 1 lbs Lean Ground Beef 1/4 cup Scallions finely diced 1 tbsp Worcestershire Sauce 1 tbsp Reduced Sodium Soy Sauce 1/2 tsp Garlic Powder 1/2 tsp Salt (optional)* 1 can Light Cooking Spray 12 medium Portobello Mushroom Caps 6 small Reduced-fat Swiss Cheese; 12 medium Portobello Mushroom Caps 6 small Reduced-fat Swiss Cheese sliced 3 small Roma tomatoes sliced 2 cup Romaine Lettuce