Boil the water: Bring water to a boil in a small pot or kettle.
Make the spice slurry: In a mug, combine the cayenne, cinnamon, chili powder, nutmeg, and hot chocolate mix. Add a splash of the boiling water and stir into a smooth, thick paste with no dry lumps.
Add the hot water: Pour in the remaining hot water and stir well until the slurry is fully dissolved into a smooth mixture.
Add the milk: Stir in evaporated milk until fully combined.
Garnish and serve: Top with whipped cream and finish with a sprinkle of sea salt. Serve hot.