Bake cookies for 8 to 10 minutes or until edges are firm. Transfer cookies to a wire rack and cool completely.
Use icing immediately. If icing starts to set, stir in a few more drops of boiling water.
To store: Place unfrosted cookies in layers separated by waxed paper in an airtight container. Store at room temperature for up to 3 days or freeze for up to 3 months. Before serving, thaw cookies, if frozen and spread with icing.