These stuffed peppers are made with all of the flavors you'd find in a philly cheesesteak sandwich. Shaved steak, caramelized onions, and bell peppers make up the filling for these amazing stuffed bell peppers, along with optional sliced mushrooms and a topping of shredded cheese. The recipe has a few cooking steps, but preparation is easy, and the list of ingredients is simple. If you like steak and cheese sandwiches, you'll love this combination, and it's gluten-freeUse fresh, good-quality, shaved steak if possible--sirloin, flank, bottom round, etc. Frozen shaved steak cooks quickly and will do in a pinch. Pepper jack cheese made up our topping, but cheddar jack, muenster, american, or your favorite melting cheese would work just fine. Or top them with cheez whiz to make them even more like the original philly cheesesteak.