Preheat broiler. Prepare as directed through Step 2. Place filled peppers, slit sides up, on the unheated rack of a broiler pan. Broil 6 to 7 inches from the heat about 5 minutes or until peppers are crisp-tender and filling is heated through. If desired, sprinkle with additional cheese.
Because chile peppers contain volatile oils that can burn your skin and eyes, avoid direct contact with them as much as possible. When working with chile peppers, wear plastic or rubber gloves. If your bare hands do touch the peppers, wash your hands and nails well with soap and warm water.