1/4 c. butter
1/4 c. onion, chopped
2 tbsp. flour
1 tsp. salt
1/8 tsp. pepper
1/4 tsp. Dijon mustard
1 c. dairy sour cream
2 pkgs. green beans, cooked, drained
2 oz.) 1/2 c.) Swiss cheese, shredded

TOPPING:

1/4 c. dry bread crumbs
1 tbsp. butter, melted

Heat oven to 350 degrees. In medium saucepan, melt 1/4 cup butter; saute onion in butter until crisp-tender. Blend in flour, salt, pepper and mustard; cook until thickened, stirring constantly. Remove from heat. Stir in sour cream, cheese and beans, mix well. Pour into ungreased 1 1/2 quart casserole. In small bowl, combine topping ingredients; sprinkle evenly over beans. Bake for 20 to 25 minutes or until crumbs are light golden brown.