I have 6 small plastic pudding basins with lids (1/2 pt/300ml size). I remember using them once but I can't remember what recipe I was making. If I use a recipe for a bigger pudding how long do you think I would need to steam these smaller puddings for and what's the best way to tell if they are done?
Christmas puddings are usually cooked for quite a long time as steaming is a very gentle and slow method of cooking. Most Christmas puddings are made with suet (shredded beef fat) and this tends to take longer to melt than butter, so the pudding needs a long cooking time to make sure that the fat has melted and combined properly with the other ingredients. Long steaming times also seem to help to develop the flavour and colour of the pudding.
The pudding will be cooked from a food safety point of view once it reaches an internal temperature of 72c/160F or above, but the flavours of the pudding may not have fully developed at this point. Most recipes suggest initially steaming smaller versions of puddings for almost as long as full sized ones, though the second steaming could be shorter. If you are using Nigella's Ultimate Christmas Pudding recipe then we would suggest steaming the smaller versions for at least 3 hours initially (vs 5 hours for a full-sized version), and 3 hours on Christmas Day, or you could vary this to 4 hours initially and 2 hours on the day or even 5 hours initially and 1 hour on the day.