"Basically" is the answer I got. It may be something steeped in with the tobacco. But it's not maple, chocolate, honey, vanilla, graham cracker, or cocoa or anything along those lines. The one thing I didn't ask him was if it was some type of coffee-ish elements in it. I don't think that's it, but it's something kinda sweet and roasted.
The reason I know those flavors are not in there is that W and I played a game where he said if I could guess it he would tell me. I guessed about 20 total things and he just kept saying "nope." Then again, he has access to sooooo many extracts, it could just be something very hard to identify. You see how quickly the Cha-Yens and Yerba Mates went up on the site after TCP requested them? That's because in his vault he has more recipes and extracts than anyone could fathom (and that's a gross understatement). I am really serious.
One time I asked him if he had heard of Blue Lotus and he said he couldn't get the extract perfect "yet!" I was like,

A Blue Lotus vape would be a game changer (especially if the alkaloids were left in it)!