Mix cocoa, sugar and salt in the drinking glass. Add enough water to make a thick sauce and add the vanilla extract. Brew the espresso and pour it in a glass. In a separate glass or cup (with a handle, may get hot), heat the milk with the steam nozzle under the surface of the milk (don't let the milk get hot enough to boil). When the milk is to the desired temperature, bring the steam nozzle closer to just below the milk's surface until the milk begins to bubble and froth. Do this until you get the desire amount of foam/froth. Add the the brewed espresso, heated and frothed milk to the glass with the chocolate sauce. Mix well and spoon any remaining froth on top. Enjoy!