It can be done but it is EXPEN$IVE as well as unnecessary. I used to do it all the time when I worked at AIB. First you document the finished product with pictures, measurements and actual samples for matching, then you collect all the information you can regarding how it’s made, every little bit helps, then, if you can get it, dissect the mix/goodie bag by dumping it out and sorting through it with a pick to identify as many ingredients as possible, now you prepare a test version and conduct a few trial bakes t fine tune your version of the mix. The short way is to just replicate the finished product paying little attention to how they make it, it’s the finished product you’re after, not the mix.
Tom Lehmann/The Dough Doctor