You’ll need good firm cake, similar to pound cake. Here’s the recipe I used
. I don’t know if it was luck, or overfilling the cupcake cups, but this cupcake came out with a nicely flat top, which is exactly what is needed (for Storm troopers instead of Clone troopers, a rounded top would be better).
Ideally, your cupcakes should be extra tall, so use a tall cupcake pan (like this one: Wilton 6 Cup Kingsize Muffin Pan
). If you don't have something like that, improvise with oven safe cups that would have a similar shape.
The cupcakes must be tall for this to work, so overfill the cups. Bake a few extra cupcakes or cake in any sort of pan, to use as cake ball mixture. Since you want smooth sides, don’t bake in muffin cups. Either grease and flour the pans very well, and/or line with strips of parchment paper (that’s what I did) to prevent sticking.