Preheat oven to 350 F. Spray 13 x 9 inch baking dish with nonstick cooking spray
Cook noodles according to package until al dente. Drain
Meanwhile cut corned beef into bite-size pieces. Combine noodles, corned beef, sauerkraut and cheese in large bown. Spread in prepared dish.
Combine dressing, milk and mustad in small bowl. Spoon dressing mixture evenly over noodle mixture.
Tear bread into large pieces. Process in food processor or blender until crumbs from. Combine bread crumbs and margarine in small bowl. Sprinkle evenly over casserole. Bake uncovered 25 to 30 mins or until heated through.