Pour the milk into a saucepan and set it over medium to medium-low heat. Whisk in the cocoa powder and sugar until the mixture is warm (not boiling) and the cocoa is fully dissolved.
Once the milk mixture is hot, reduce the heat slightly and add the chocolate chips. Whisk constantly until they’re completely melted and the mixture looks silky and smooth.
Add the vanilla extract at the end for that perfect finishing touch. Give it one last whisk, then pour the hot chocolate into your favorite mugs and top it however you like.