How to cook
Cut the puff pastry into 3 equal squares. Pierce the surface with a fork. Arrange the squares in a tray lined with baking paper and bake them at 390°F (200°C) in a preheated oven until they're fully baked.
Remove the crusts and let them cool.
Make your lemon cream. Pour the milk into a saucepan.
Add the sugar, egg yolks and a full teaspoon of starch and a full teaspoon of flour. Put the saucepan on the stove and start stirring immediately until the confectionery cream thickens.
During cooking, add 2 tablespoons of lemon juice (optional).
Remove the finished cream from the heat and flavor it with a vanilla and the grated peel of 1 lemon. Allow the cream to cool.
Whip the cream well. Add the whipped cream in portions to the cooled cream.
Put a puff pastry in a suitable tray. Fill a piping bag with cream and cover the crust. Put the other crust and pipe out the cream again.
Cover with the third crust.
It is good for a mille-feuille with lemon cream to stand for a day before being consumed.