In a small saucepan, heat the milk over medium heat until hot but not boiling.
In a separate bowl, whisk together the cocoa powder, sugar, cinnamon, vanilla extract, and chili powder (if using).
Gradually whisk the cocoa mixture into the hot milk until well combined.
Continue to heat the mixture for another 5 minutes, stirring occasionally.
Remove from heat and pour the hot chocolate into mugs.
Top with whipped cream and garnish with cinnamon sticks.
Serve immediately and enjoy!