Step 1

In a medium saucepan, stir together the milk, sugar, cinnamon, and espresso powder. Bring to a simmer over medium to medium low heat. Just enough to bubble slightly but a boil.

Step 2

Remove the pan from the heat, add the chopped chocolate and let it stand for a couple minutes to melt the chocolate. Whisk until smooth, then pour into warmed mugs.

Step 3

Top with a marshmallow and serve.