An encounter between an espresso and an excellent hot chocolate with an enjoyable hot-cold contrast. Prepare the espresso. Emulsify briefly the milk, cocoa and liquid sugar in a milk foamer switched in heating mode until the cocoa dissolves completely. Add the coffee to the shaker, mix cold and pour the contents into the large freddo glass. Whip up the milk froth and pour it into the glass until full. Garnish with a sprinkle of cocoa powder.