Make mini whoopee pies. Prepare batter following recipe directions. Bake and cool according to pan package directions.
Assemble treat pops. Prepare buttercream icing following recipe directions. Push mini whoopee pie into bottom of treat pop. Use tip 12 and chocolate icing to pipe a swirl of icing from back edge following the curves of the container, then filling the center. Repeat to add two more layers of cake and icing. Use tip 1M and chocolate icing to pipe swirl on top of treat pop.