320 g ready-rolled all-butter puff pastry
3 tbsp icing sugar
290 ml full fat milk
2 egg yolks
55 g caster sugar
20 g plain flour
20 g cornflour
Seeds from 1 vanilla pod
160 ml double cream
200 g fresh berries
Preheat the oven to 200°C/180°C fan.
Unroll the pastry and place on baking parchment on a non-stick baking tray. Dust generously with icing sugar, prick all over with a fork, and cover with a second sheet of baking parchment. Weigh down with a heavy baking tray and bake in the oven for 20 minutes. Remove and leave to cool on a wire rack.
Scald the milk (heat to just below boiling) in a saucepan.
Mix together the eggs, sugar, flour and cornflour in a bowl. Slowly pour over the hot milk and whisk well.
Rinse out the saucepan, then return the eggy mix to the pan and bring to the boil. Cook for 1 minute, stirring vigorously, until the sauce thickens, then pass through a sieve into a cold clean bowl. Stir in the vanilla seeds, cover with greaseproof paper to prevent a skin forming, and leave to cool completely.
Whip the double cream to soft peaks. Beat the cold crème pâtissière with electric beaters, then fold in the double cream. Spoon into a piping bag and chill until ready to use.
When the pastry has cooled, slice it gently into 3 equal-sized lengths with a bread knife.
Assemble the mille feuille just before serving. Add a dot of cream to the serving plate and put a piece of pastry on top. Place the berries around the edge, then pipe a layer of cream between them. Place the second pastry layer on top and repeat. Finish with a top layer of pastry. Either dot more crème pâtissière over the top or dust with icing sugar or raspberry powder.