How can I make a panna cotta based on Jelly bellys?
Grant Achatz does quite a lot with popcorn at Alinea. One of his recipes is available as part of the preview of his book on Google Books and is just about readable. Looks like he goes with the steeping method (although he's using water). I ate at Alinea recently and there was a popcorn soup on the menu that tasted exactly like popcorn, so it's probably a good place to start (continue?).  

A friend once made a "Movie Theatre" Panna Cotta. It was a normal panna cotta, but he served it with a Coca Cola syrup (just heavily reduced Coke) and some home made Cracker Jacks. It was delicious. So good luck with yours. 

Edit:
The basics of the recipe:


Cook 100g uncooked popcorn kernels (he does it stove top with 25g canola oil)
Add to 750g water, 7g kosher salt, 90g butter, 75g sugar. Simmer for 5 minutes
Strain through china cap, blend, strain through chinoise.