To get rid of that chalky, scuffed look on chocolate, use a heat gun on low. Be careful, though- you don’t want to scorch your chocolate! Go slow and keep a distance of about a foot or so between the chocolate and the gun.
Pro-tip: make sure you don’t have any strategically placed crumbs in your shot or the heat gun will mess up your perfect composition. Think of it like a less blowy hair dryer. 😉