In a small saucepan, whisk together the cocoa powder, sugar, salt, and cinnamon (if using).
1 tablespoon unsweetened cocoa powder, 1-2 tablespoons granulated sugar, 1 pinch salt, 1 pinch cinnamon
Pour the heavy cream and cold milk into the saucepan.
2 tablespoons heavy cream, 1 cup milk
Turn the heat to medium and start whisking immediately.
Keep whisking as the milk warms up. The powder will eventually dissolve completely into the liquid.
Heat until you see steam rising and small bubbles around the edge. Do not let it boil over.
Remove from heat, stir in the vanilla extract (if using), pour into your mug, and enjoy!
¼ teaspoon vanilla extract