Place the milk in a saucepan with the cinnamon stick and chillies. Carefully bring to a very gentle simmer for one minute. Take off the heat and leave to one side for five minutes so the flavours infuse.
Reheat, then remove the cinnamon, keeping the chillies. Add the chocolate and stir in until it melts, add the sugar and mix.
If you want to go for total luxury and a real one-off treat then top with a spoon of whipped cream, a dusting of chocolate and decorate with a half chilli.