Preheat your oven to 350 degrees F and grease your muffin tin. Set aside.
In a pan over medium heat, sauté diced onion and green pepper in olive oil. Cook until softened, then add in the shaved steak. Season with salt, pepper, and garlic powder.
Once the steak is cooked, remove from the heat, and add in cream cheese and 1 cup of shredded mozzarella. Mix until the cream cheese coats the meat mixture.
Place your wonton wrappers inside the greased muffin tin. Spoon in the cheesesteak mixture, then top each one with remaining shredded mozzarella. Bake for 12 minutes.