Russian Napoleon cake (Tort Napoleon)

1. For the cream, bring half the milk to the boil with the seeds scraped from the vanilla pod and the split pod. In a bowl, whisk the eggs with the sugar and flour until smooth, then add the rest of the cold milk.

2. Pour the hot milk into the egg mixture in a thin stream, whisking constantly, return it to the pan and cook over low heat, stirring all the time, for 5-7 minutes until you have a thick custard. Remove the vanilla pod, cover the surface with cling film and let it cool completely.

3. Preheat the oven to 200 °C. Divide the puff pastry into 8 pieces, roll each out on baking paper into a thin round of about 24 cm, prick all over with a fork and bake for 10-12 minutes until golden; while still warm, trim into a circle around a plate and set the offcuts aside.

4. Beat the soft butter until fluffy, then work in the cooled custard a spoonful at a time – you'll get a silky, light butter cream.

5. Stack the layers, spreading each thickly with cream, cover the top and sides too, and finally sprinkle with the crushed pastry offcuts.

6. Chill for at least 8 hours, preferably overnight, so the layers soften, then serve in slices.

Tip: The cake became popular in Moscow in 1912, at the centenary of the victory over Napoleon – legend has it that its triangular slices were shaped like the emperor's hat; with shop-bought all-butter puff pastry it's easy to make at home.