1Heat oven to 400^. Spray 8-inch square of a 2-quart glass baking dish with cooking spray.
In medium bowl, stir Bisquick, milk, egg, and 1 teaspoon of the caraway seed with fork until blended. Spread 1 cup batter in baking dish.
Brush corned beef slices with mustard; layer on top of batter in baking dish Top evenly with cheese and sauerkraut. Carefully spread remaining batter over sauerkraut. Sprinkle with remaining 1 teaspoon caraway seed.
Bake uncovered 28-32 minutes or until light golden brown and center is set. Let stand 5 minutes before cutting. Serve with Thousand Island dressing.