Add the cocoa powder and sugar to a heavy pot. Whisk in just enough water to form a thick paste. Heat over a low flame, stirring stirring constantly. The paste will bubble gently and after a minute or two, it should darken in color as the sugar begins to caramelize.

Now add the milk, little by little, whisking vigorously so that the chocolate paste and milk are completely amalgamated. Let the mixture heat up, until it is just about to boil—but remove it from the heat just before it does. The liquid should be quite thick and very dark in color.

While the liquid is heating, whip the cream, sugar and (if using) extract in a standing mixer until stiff.

Pour the hot chocolate into a cup (or mug) then top with a generous dollop of whipped cream, and enjoy right away!