In small bowl, mix powdered sugar and water until smooth. Spread or pipe glaze onto 8 of the cookies to look like skull and crossbones. With black icing, pipe eyes, nose and mouth. Cut out 8 ice cream shapes with skull-and-crossbones cutter. Place on bottoms of 8 plain cookies. Top with decorated cookies, flat side down; gently press together. Wrap in plastic wrap; store in freezer.