Add all the ingredients into a small pot over., whisk together until all of the sugar has dissolved and the cocoa powder is no longer lumpy.
Bring to a boil. Continue stirring as the mixture boils. Do not walk away and let pot boil over. Lower heat to medium and continue stirring. After 2 minutes, remove pot from heat.
Transfer the pot into a glass measuring cup. Then pour the hot chocolate into mugs for serving.
Top with your favourite toppings. Whip cream, marshmallows, grated chocolate, etc.