This is just long slips of puff pastry stuffed with whatever you want, squirreled up into a baking dish to look like neatly-packed intestines. The key point is that after you've packed it all in, you get a thin brush and paint on 'blood' with red food colouring - it's surprisingly effective.
The stuffing can be anything from savoury mince mix to nuts and custard. Just not too runny to be packed in. Could be fruity, could be sausagey, could be stuffing mix with apricots and pinenuts.
The sheets of puff pastry should probably be cut no thinner than about 15 cm wide, or you'll have trouble keeping the stuffing in. A lot of recipes for this insist that you lay the whole thing out into one long strip before winding it up - this isn't exactly necessary and makes it very difficult to transfer to the baking dish. Just flummox the seams in when you put it into the dish and save yourself a lot of trouble - spend a little more time painting on the fake 'blood' instead, much more worthwhile.
