Sour Cream Green Beans

1 onion, thinly sliced
1/2 cup butter or margarine, divided
2 (10 ounce) packages frozen green beans, thawed and drained
1 cup dairy sour cream
1/4 cup flour
1 1/2 teaspoons salt
1/4 teaspoon pepper
1 cup shredded sharp natural Cheddar cheese
1 cup soft bread crumbs

Saute onion in 1/4 cup butter or margarine. Add to combined beans, sour cream, flour and seasonings; mix lightly. Pour into greased 1 1/2-quart casserole. Sprinkle with cheese; top with crumbs tossed with 1/4 cup melted butter. Bake at 350 degrees F for 25 minutes.

Makes 4 to 6 servings.