While Frank's material is quite good, imho it's still not that convincing. I guess Charless has to compete again against other software. And, again, chocolate would highly benefit from SSS. With that it's actually not that difficult to create a good chocolate material as long as you have something of a specialist around who can advise you (if the mouth of your victim starts to water, you're near there).
Second is the problem with all product shots: It should look convincing but without the real blemishes of such a material (which, of course is a contradiction).
So in Cheetah I'd try to simulate sss with some very slight luminositiy in a lighter brown, maybe controlled through a texture map to get some subtle variation (the emphasis is on subtle).
Second chocolate is a very greasy material, so it's very shiny, but also very blurred. Depending on the quality of the chocolate (i. e. what are the ingredients? How much is the percentage of cocoa vs cheaper stuff like (evil) palm oil and so on) that varies very much. So you'd need at least a photography of the real stuff that's actually depicted to know how it should shine and how blurry it really is (if no photo is available, you use just some expensive high quality dark chocolate).
Maybe I'd try something in addition to this. Buy a bar of high quality chocolate and first of course do what I usually do: Stare at it and try to see what's special about it, try to understand it, and as esoteric as it sounds, try to understand it.
While that could be done with any dark chocolate you like, even with nuts, the next part would need a simple dark chocolate without any other ingredients (like salt, chili or whatever they put in it nowadays). Just plain, bitter, dark chocolate.
Before you eat it, try to photograph the backside in a very diffuse light, without any visible highlights on it. Cloudy days at noon can be very good for that. Create a texture from that and more or less use it as Frank has done (with some changes to the roughness, of course). (the backside is usually one smooth surface).
If you are like me and don't like dark chocolate very much (well, in real good quality I start to like it), find somebody else who is willing to eat it after all you have done with it on the way.
Good luck