It's rare that a spice makes the headlines but cinnamon is a recent exception - and not in a good way. For those who haven't heard of it, the cinnamon challenge is an absolutely idiotic stunt involving people filming themselves while attempting to swallow a teaspoonful of ground cinnamon in less than 60 seconds, without water, then posting the video on the internet. Although the challenge sounds easy enough, it isn't, and ingesting such a large quantity of the finely ground powder can lead to choking and lung problems. Most of the news items about the cinnamon challenge have been warning people against attempting it.
Cinnamon, when used in more modest quantities, is delicious. It comes from the bark of the Cinnamomum zeylanicum plant and is often called Ceylon or Sri Lankan cinnamon. However, there are several other plants - from China, Indonesia and Vietnam - whose bark is also called cinnamon, even though it is, in fact, cassia. True cinnamon is considered far superior to cassia and has a finer, thinner, more delicate texture (if it's in stick form, as opposed to the ground spice), and a sweeter, warmer, less bitter taste. Cassia is darker in colour and the layers of bark are much thicker. True cinnamon is difficult to find and most of the stuff sold in supermarkets, whether it's the ground spice or cinnamon sticks, is actually cassia. The latter has a much higher amount of coumarin, a compound that can adversely affect the liver and kidneys if taken in large quantities - if you have a predisposition to problems with those organs, you should probably avoid the spice entirely.
Cinnamon, whether real or otherwise, should be used sparingly because it can easily overwhelm other flavours. It is one of the ingredients in five-spice powder, and it's used in pain d'epices, gingerbread and spice cookies. One of my favourite ways to eat it is in (what else?) cinnamon rolls, which I make with normal croissant dough. Roll out the dough until it's about 8mm thick then brush it with melted butter. Sprinkle with granulated sugar that's been mixed with a small amount of ground cinnamon (or cassia), then roll it up and seal the edge. Cut the roll into 4cm pieces, put them cut-side up in a muffin tin and leave until risen and puffy. Bake until done then turn them out of the pan. Brush the rolls with melted butter then dust them with cinnamon sugar and shake off the excess. These should be eaten warm.