Unsweetened whipped cream and ground cinnamon, for topping (optional)
Combine the milk, cocoa powder, dates, vanilla and a pinch of salt in a medium saucepan. Heat the mixture over medium heat, stirring frequently, until hot and steaming. Continue to cook, without letting the mixture boil, giving the dates time to soften, another 5 minutes.
Let cool for 5 minutes or so, then transfer the mixture to a blender and being careful of the hot liquid, puree until smooth. You can strain the mixture to catch any small chunks of dates that weren't blended.
Pour into mugs and top each with whipped cream and a sprinkle of cinnamon, if using.
BLENDING HOT LIQUIDS:When blending hot liquids, remove liquid from the heat and allow to cool for at least 5 minutes. Transfer liquid to a blender or food processor and fill it no more than halfway. If using a blender, release one corner of the lid; that prevents the vacuum effect that creates heat explosions. Place a towel over the top of the machine, pulse a few times, then process on high speed until smooth.