Bring the milk to the boil with the butter, salt and sugar.
Tip in the flour all at once, and cook over high heat, stirring with a wooden spoon, until the mixture pulls away from the side of the pan and forms a smooth ball, about 1-2 minutes.
Remove from the heat, let cool slightly, then mix in the lemon zest, the whole egg, and the two egg yolks one at a time, beating thoroughly after each, until smooth and glossy.
Using a teaspoon, pipe walnut-sized mounds onto a buttered baking tray, spaced 4-5 cm apart.
Bake in a 180°C preheated oven for 20-25 minutes; do not open the oven in the first half of baking or they will collapse - check towards the end that they are golden and dry.
Transfer to a rack and let cool completely.
Whip the cream with the icing sugar to stiff peaks, and fill the cooled puffs with it, using a piping bag or teaspoon.
Cook the chocolate with the sugar and water over low heat into a thick, glossy glaze, stirring, until the sugar dissolves and it thickens slightly.
Drizzle the filled puffs with the still-warm chocolate glaze, and serve at once.
Based on: Malatinszky Fanny szakácskönyve (a classic Hungarian cookbook), modernised. Calories and protein are estimated.