This is the ultimate winter warmer! Perfect for when you come in from the cold.
Bring milk, cinnamon stick, cocoa, and vanilla to a boil in a medium saucepan over medium-high heat, stirring occasionally. Remove from heat and stir in the chopped chocolate until melted. Add chili powder, if desired. Discard the cinnamon stick and serve. Top with marshmallows or a dollop of cream.