In a small dish, combine the cocoa powder, sugar, salt, ground ginger, cinnamon, and nutmeg.
Make the hot cocoa:
In a medium saucepan over medium heat, whisk the water and the cocoa powder, sugar, and spices mixture. Continue stirring constantly until the cocoa powder and sugar have turned into a liquid chocolatey mixture.
Pour in the milk, and warm it up over medium heat until it's hot -do not boil it, or you'll risk burning the milk.
Turn off the heat and stir in the vanilla. Pour into mugs and serve immediately.
Notes
For one: in the bottom of a mug, mix 2 teaspoons of cocoa powder, 2 tablespoons of sugar, ½ teaspoon ground ginger, ¼ teaspoon cinnamon, and a pinch of nutmeg. Heat 1 ¼ cups of milk until hot but not boiling (in the microwave or stovetop). Pour a little bit of the hot milk, just enough to cover the powdered mixture, and with a spoon or small whisk, until the cocoa, sugar, and spices have dissolved. Then, add ¼ teaspoon of vanilla pour the rest of the hot milk into the mug, and stir to combine.