Prepare the chicken. In a large sauté pan on medium heat, add toil and sauté the onions and green pepper. Season the veggies with garlic salt and pepper. Add chicken and chicken stock. Lower heat and let simmer for 10 minutes. Turn off heat.
Assemble the sandwiches. Preheat broiler. Split the rolls open. Put 1/4 of the chicken mixture onto each roll. Top with cheese and banana peppers. Close the sandwiches and individually wrap them in foil. Put the sandwiches into the oven for 5 minutes.