Prepare and roll out cookie dough. Cut cookies using skull cutter. Bake and cool.
Use tip 3 and full-strength white color flow icing to outline cookie. Use thinned white color flow icing in cut parchment bag to flow in cookie. Let dry.
Use tip 3 and full-strength black color flow icing to pipe in eyes and nose. Pat smooth with finger dipped in cornstarch. Use tip 2 and full-strength black color flow icing to pipe outline mouth and crack.