Traditional Reuben Casserole Recipe

Preheat oven to 350°. Lightly grease a 9x13 in baking dish. Mix the thousand island dressing, sour cream and onion in a bowl. Arrrange the dark and light rye bread cubes in the bottom of the prepared baking, reserving about 1/2 C each for topping. Layer the bread with sauerkraut and corned beef. Spread the dressing mixture over the corned beef. Sprinkle with Swiss cheese, top with remaining bread cubes and drizzle with margarine. Cover and bake 15 minutes in the preheated oven. Uncover and continue baking 10 minutes, or until bubbly and lightly browned.