PREPARE cake batter and bake as directed on package for 2 (9-inch) round cake layers. Cool in pans 10 min. Invert cakes onto wire racks; gently remove pans. Cool cakes completely.
STACK cake layers on plate, spreading jam between layers. Cut cake in half. Stack regular Oreo Cookies in line down centre of large cake board or tray for the butterfly's body, securing cookies to each other with small amount of Cool Whip. Arrange cake stacks around body for the wings.
SPREAD remaining Cool Whip onto cake stacks. Decorate wings with remaining ingredients. Keep refrigerated.