Peel thick slices of the orange rind with a knife or vegetable peeler, and place in a saucepan with the milk and chilli flakes.
Bring to the boil, then remove the pan from the heat and allow the flavours to infuse for at least 5 minutes.
Whisk in the drinking chocolate powder until smooth and return the pan to the hob to warm through.
Pour the hot chocolate through a sieve to remove the peel and chilli flakes, then serve in mugs with orange slices and extra sprinklings of chilli flakes (if you like it spicy!).
Cook's tip: You could easily multiply this recipe to feed a crowd at a Bonfire night party.