I tried mint syrup as a kid and wasn't impressed. I was therefore not overly excited to find that De Kuyper alcoholic creme de menthe is vegan a month or so ago when @M_tohappyvegans wrote to them to check. It turns out that both the white stuff (which I've never seen in shops) is vegan, as well as the green stuff (in most supermarkets).
As part of my quest to own all vegan suitable booze I bought a bottle anyway, and was pleasantly surprised.
It mixes incredibly well with chocolatey things, such as chocolate soya milk. I plan to make a mint chocolate torte at some point (I've still not made this again since I blogged it back in Feb).
I've drunk half a bottle so far (with help) and will no doubt find other combinations that work well with it.
Edit: Now I think about it - I've actually made quite a few good tasting cocktails using this now. Too bad I can't remember how to make any of them.....
Good to see you posting again. Mint flavoured hot chocolate sounds amazing!