Preparation:

One teaspoon of cocoa powder and two teaspoons of sugar in a large or even extra-large cup. Boil water and pour up to about 3/4 of the cup. Take a milk carton (if full, empty it a little bit) and shake well.

Add the milk: don't pour straight down but press on the tilted carton so that the foam drifts down into the cup – you can use a teaspoon to help it down.