Fill a piping bag fitted with a round nozzle about 2.5 cm and pipe "logs" roughly 10 cm long onto a baking tray lined with parchment paper. Leave enough space between each one, as the pastry puffs up quite a bit.

Take the shortcrust dough out of the fridge, knead it briefly, then roll it out to a thickness of 1–2 mm. Cut out rectangles about 4 cm x 12 cm and place one on top of each piped choux log.

Bake in an oven preheated to 180°C until golden. In my oven this took about 30 minutes. Remove from the oven and let cool completely before filling.

Whisk together the egg yolks and sugar, then add the cornstarch and beat until the mixture is pale yellow and has thickened. Pour the milk into a saucepan. Split the vanilla pod lengthwise, add the seeds to the milk and bring to the boil.

Slowly pour the hot milk into the yolk mixture, whisking constantly. Pour everything back into the saucepan and bring to the boil, stirring the whole time. Cook until the cream thickens, then whisk in the butter. Cover with plastic film and let cool.

Whip the cream and fold it into the cooled pastry cream. Fill the prepared éclairs by piercing three small holes with the piping nozzle and injecting the cream inside. Dust with icing sugar just before serving.

Éclairs are best filled right before serving – if you keep filled ones in the fridge for too long, the pastry turns soggy and loses its charm. Store unfilled shells in an airtight container.