PREHEAT oven to 350° F.
MICROWAVE broken baking bars in a medium, uncovered, microwave-safe bowl on HIGH (100%) power for 1 minute; STIR. If pieces retain some of their shape, microwave at additional 10- to 15-second intervals, stirring just until smooth. Cool to room temperature.
COMBINE flour, baking soda and salt in a medium bowl. Beat butter and sugar in a small mixing bowl until creamy; beat in corn syrup and melted chocolate. Alternately beat in flour mixture and water. Shape dough into 2 round discs; wrap in plastic wrap. Refrigerate for about 1 hour or until firm.
ROLL each disc to 1/4-inch thickness between two sheets of waxed paper. Cut with cookie cutters; place on ungreased baking sheets. Refrigerate if dough becomes too soft.
BAKE for 6 to 8 minutes or until set. Cool on baking sheets for 2 minutes; remove to wire racks to cool completely. Decorate as desired.