See those sad looking cookies in the first photo, there? That's what they looked like, straight out of the package. And then see that second photo down there? That's after using my trusty heat gun on the chocolate, (and, I won't lie, doing a little Photoshop touch up for some of the harder blemishes.)
A heat gun is an awesome food styling tool for melting butter or softening cheese on set, or for my favorite-- giving chocolate a nice shine. The trick is not over-melt things, which can happen pretty easily, so you have to be careful. Also, heat guns blow hot air, so if you have carefully placed crumbs or lighter objects in your shot, you may want to cover them while you use the heat gun or they will blow away.
Now that you have learned this little trick of the trade, I guarantee you will start noticing the melty shine on chocolate in books and magazines everywhere.
Go forth and melt! :)