Polish "bird's milk" chocolate-covered soufflé (Ptasie mleczko)

1. Soak the gelatine leaves in cold water for 10 minutes. Line a 20×20 cm tin with baking paper.

2. Beat the soft butter with the seeds scraped from the vanilla pod until fluffy and set aside (at room temperature).

3. Squeeze out the gelatine leaves and dissolve them in a small pan with 3 tablespoons of water over low heat (without boiling); let cool slightly.

4. Whisk the egg whites to stiff peaks, then add the sugar a little at a time and whisk to a glossy, thick meringue. Pour in the lukewarm gelatine in a thin stream, whisking all the time, and finally work in the butter a spoonful at a time. Smooth the mixture into the tin and chill for 1 hour until set.

5. For the glaze, bring the cream to the boil, take off the heat, break in the chocolate and stir until smooth; let it cool slightly, then pour over the set soufflé and smooth it out. Chill for at least another 2 hours.

6. Cut into squares with a knife dipped in hot water and serve cold.

Tip: Ptasie mleczko ("bird's milk") takes its name from an old saying: someone who has everything lacks only bird's milk – born in Warsaw in 1936, the sweet became one of Poland's favourite confections, and thanks to the egg whites it is as light as its name suggests.