Heat oven to 400°F. In ungreased 8-inch square (2-quart) glass baking dish, stir together chicken, beans, tomatoes and corn. Stir 1 tablespoon Bisquick mix and reserved tomato liquid until blended; stir into chicken mixture.
In medium bowl, stir together 1 cup Bisquick, the milk and egg until blended. Pour over chicken mixture in baking dish.
Bake uncovered 25 to 30 minutes or until golden brown.