Question Author
Thanks to you all for these three very different suggestions.
I've printed off the recipe, BBWCHATT, and will certainly try it out for something a bit special as it sounds delicious - though I imagine that the ski restaurants on the slopes probably won't go to that amount of effort and will use something commercial.
I'll also fork out and try the Charbonnel et Walker, KenR, if I can get source it locally (not having a Sainsburys or Waitrose).
Your answer, Pieeater, sounds quick and simple though I wonder if it becomes thick. I'll try it out and see!