makes 4 dozen squares.
- Melted chocolate or chocolate icing and white icing in large bowl of electric mixer, combine cookie mix, egg and vanilla.
- At low speed, beat until mixture forms a dough.
- Divide dough in half; remove one half from bowl.
- To dough in bowl, add cocoa powder; knead to mix well.
- On work surface, on separate sheets of waxed paper, roll each half of dough to 9x6" rectangle.
- Using paper to lift dough, invert plain dough onto top of chocolate dough.
- Remove paper from plain dough.
- Using long chef's knife, cut doughs lengthwise into 2" wide strips.
- Stack strips, removing waxed paper and alternating colors.
- Cut stack lengthwise into three equal strips.
- Stack strips so colors alternate; gently press stack so dough layers stick together.
- Wrap stack in plastic wrap; refrigerate 2 hours.
- Preheat oven to 375°F.
- Lightly grease 2 baking sheets.
- Remove plastic wrap from dough; cut stack crosswise into ¼" slices.
- Place slices checkerboard side down on prepared baking sheets; bake 8 minutes or until golden.
- Transfer to wire rack to cool.
- With pastry bag and writing, decorate cookies with dots of chocolate and icing.