Write a birthday message on small piece of paper. Then, attach to toothpick and insert into cake.
Add a lunar lake by cutting out a 1-1/2-inch deep by 2-inch-wide well in center of top of assembled cake before frosting with remaining COOL WHIP mixture. Insert a JELL-O X-Treme Blue Raspberry Gelatin Flavor Snack in hole. Decorate with remaining ingredients as directed.
Cake can be decorated ahead of time. Just add cookie decorations just before before serving. Refrigerate leftovers.