I made these for my cousin Teela's twin sons' 3rd birthday party! It was carnival themed, so the popcorn idea was perfect! Teela gave me the idea, and I found help at Cake Central.
The cupcakes are buttery pound cake with extra buttery buttercream on top (I added Wilton Butter Flavor to everything haha). The "popcorn" is actually just yellow and white miniature marshmallows that were cut crosswise at the bottom and smooshed to look like popcorn.
Teela made some great cupcakes too, with the most adorable little toppers!