In a second medium sized bowl, add the chocolate. Pour hot coffee over top, and stir until the chocolate is completely melted.
Stack the bowl with the chocolate on top of the ice water to cool, and whisk vigorously, for five minutes. It will begin to thicken.
Remove from the ice water and stir until you get a fluffy mousse consistency. Transfer to bowls or cups and enjoy immediately, or store in the fridge for up to 4 days. It is also delicious with orange zest on top.
Don't be afraid to get creative with the toppings.
If you avoid caffeine, you can use decaf tea or coffee. You can even get scrappy and melt the chocolate with date seed coffee.
Be sure to check the ingredients when you purchase the chocolate. Dark chocolate is usually vegan-friendly, but some manufacturers sneak in dairy fats or milk powder into the mix.