My older sister was allergic to dairy when we were young, so things like chocolate etc. were rarely on offer! My mum used to go to health food shops and buy banana chips, dried fruit, carob bars etc. That was over 20 years ago, and things are much more widely available now in supermarkets etc. I do remember that my nan (marvellous cook!) used to buy dairy free marg (Tomor I think) and a horrendous milk substitute made from plants. Again, I'm sure that there are better alternatives around today! Nan used to make a dairy free flan case and fill it with fruit for Sunday tea - I would still choose the fruit flan over chocolate cake to this day! Sorry no specific recipes, but I would suggest having tasty treats that all the kids can enjoy, rather than singling him out.