Use a cut lemon or some water to wet the rim of your serving glass.
Dip the rim into the cinnamon sugar so it sticks to the wet spots.
Add ice to the serving glass, and then add in the apple cider, Fireball, lemon juice and bitters.
Give everything a stir with a long bar spoon.
Add a cinnamon stick for garnish, and serve!
Notes
For a warm version, heat up the apple cider in a saucepan until it starts just bubbling around the edges. Pour it into a mug, and then add the Fireball, lemon juice and bitters.
Try using a bar spoon of apple cider vinegar instead of the lemon juice for even more apple flavor!