Gender reveal party. I still like a cake for the actual reveal. And having the ultrasound tech write boy or girl in a sealed envelope for the baker, so no one at the party knows what it is until the reveal.
These Gender Reveal Cupcakes have pink, blue, and white swirled frosting on top that hides the secret colored heart in the center of the cupcake revealing the baby's gender when you bite into it! (Step-by-Step Photo Tutorial)