Make a small slice in the centre of a wedge of lime and run it around the rim of a heatproof mug. Combine sugar and cinnamon in a small saucer or wide and shallow bowl. Dip rim of heatproof mug in the cinnamon sugar mix until rim is well-covered.
Add water a small saucepan over medium heat, bring to a boil. Add 6 tbsp of Mayan drinking chocolate. Reduce heat to a simmer and whisk until thick and smooth.
Add milk to liquid chocolate and whisk until milk and chocolate are combined and milk is heated through, about 3-5 minutes.
Add 1 oz of mezcal to prepared heatproof mug, pour in hot chocolate, garnish with cinnamon stick and marshmallows, as desired. Enjoy!