Place the cinnamon stick and powder into a frying pan over medium high heat. Toast for around three minutes or until very, very fragrant. Remove from the heat.
Place all the remaining ingredients in a large bowl or saucepan along with the hot cinnamon stick and powder. Pour over the boiling water and cover - leave for 4-5 hours.
Using a high speed blender, blitz everything together until very smooth. If your blender is small, do it in two batches.
Pour the blended liquid through a fine nut milk bag or muslin, straining out all the nut meal. Discard the nut meal. Pour it into a glass bottle, chill for at least an hour and keep in the fridge for when you need some serious comfort.
Serve it over ice or heat it and serve with a slosh of rum or mescal. I have mine in the morning over ice with a double shot of espresso.