Make around 35ml espresso using a coffee machine and pour into the base of your cup. Add the drinking chocolate and mix well until smooth.
Steam the milk with the steamer attachment so that it has around 4-6cm of foam on top. Hold the jug so that the spout is about 3-4cm above the cup and pour the milk in steadily. As the volume within the cup increases, bring the jug as close to the surface of the drink as possible whilst aiming into the centre. Once the milk jug is almost touching the surface of the coffee, tilt to speed up the rate of pour. As you accelerate, the milk will hit the back of the cup and start naturally folding in on itself to create a pattern on the top.