Marinate the chicken in the shawarma seasoning for at least 1 hour. Then cook the chicken in a pan over medium heat until lightly browned, then remove from the pan.

Add the onion, tomatoes, and green bell pepper to the pan. Once they are softened, return the chicken to the pan and mix everything together.

Fill the flour tortillas with the chicken mixture. Add cheddar and mozzarella cheese. Heat the sandwiches on a grill or panini press until the cheese melts.