1In a medium saucepan, combine the whole milk, cocoa powder, and sugar.
Heat the mixture over medium heat, stirring constantly, until the sugar and cocoa powder are fully dissolved.
Add the dark chocolate chips to the saucepan and continue to stir until the chocolate is completely melted and the mixture is smooth.
Remove the saucepan from the heat and stir in the vanilla extract.
Pour the hot chocolate into mugs and serve immediately. Optionally, top with whipped cream or marshmallows.