Meanwhile, in a medium bowl combine next six ingredients (through Cajun seasoning).
Turn over pepper halves and arrange in half of the pan. Fill with sausage mixture, allowing some filling to spill into pan if necessary. Place green beans in other half of pan. Drizzle beans with oil and sprinkle with salt and black pepper; toss to coat.
Cover loosely with foil and roast 25 minutes. Remove foil. If desired, sprinkle peppers with cheese. Roast 5 minutes more or until filling is heated through and beans are tender.