In a medium pot, mix together the cocoa powder, sugar, ground cinnamon, ground nutmeg, salt, and cayenne (see note 2).
Place on stovetop, heating to medium. Gradually add a few tablespoons of milk to the mixture, whisking to create a smooth, lump-free paste. Continue adding the rest of the milk gradually. Gently heat the mixture to your preferred drinking temperature, making sure it doesn’t reach a boil.
Remove the pot from heat and, if using, stir in the vanilla extract.
Serve hot, topped with whipped cream and a cinnamon stick for garnish, if desired. (Cocoa tends to settle over time, so it requires a good whisk before serving again.)
Notes
Note 1: Dutch-process cocoa powder, treated with an alkalizing agent, is less acidic and bitter, with a richer color and flavor. It’s darker, smoother, and mixes easily in liquids, ideal for this recipe. Hershey’s® “Special Dark” cocoa powder is a great, easily accessible option, or here's my favorite cocoa powder.Note 2: Adjust the chili powder or cayenne pepper to your preference for spiciness, and the sugar for sweetness. Remember, the whipped cream (if used) will also add a bit of sweetness.Nutrition Note: Nutrition information does not include any of the optional toppings.Storage: Allow the hot chocolate to cool before storing it in an airtight container in the fridge for 4–5 days. Reheat using low heat in a saucepan, microwave, or slow cooker, making sure not to let it boil. Give it a thorough whisk before serving.