Heat oven to 350°F. Melt margarine in large saucepan over medium heat. Add celery and onion; cook and stir 3 minutes or until crisp-tender.
Stir in all remaining casserole ingredients. Pour into ungreased 1 1/2- or 2-quart casserole.
Bake at 350°F. for 30 to 35 minutes or until thoroughly heated. Sprinkle topping ingredients evenly over casserole. Bake an additional 5 minutes or until topping is warm.