Tall cupcakes that have height to them
It's all about getting the absolute optimum amount of batter into each cupcake. Can you make one experimental batch before the "real" one? If so, very, very carefully measure infinitesimally larger amounts of batter in successive cupcakes. Take careful notes. One of the cupcakes will be perfect; use that measurement for all cupcakes in the next batch. If you've got a digital scale, this is a good reason to whip it out.