Preheat the oven to 200°C.
Lay the puff pastry on to a lined baking tray and then cover with a sheet of baking parchment and a second tray. Transfer to the oven and cook for 20 minutes.
Once cooked, cut the pastry into 18 rectangles of equal size. Sprinkle with icing sugar and then return to the oven for 3 to 4 minutes to caramelise the sugar. Set aside.
For the crème pâtissière: place the milk and chestnut cream in a pan and bring to the boil. Split the vanilla pod in half and scrape out the seeds. Add the pod to the pan.
In a bowl, beat together the eggs and the sugar before adding the vanilla seeds. Whisk vigorously and then add the flour followed by the hot chestnut milk. Return the mixture to the pan and bring to the boil. Cook for 3 minutes, stirring constantly. Pour the cream into a tray and cover with cling film, pressing the film down to remove any air. Chill for an hour.
After 1 hour, stir the crème pâtissière until smooth. Whip the cream to soft peaks. Gently fold the cream into the crème pâtissière and transfer to a piping bag.
For the caramel: in a pan, melt the sugar without stirring until you have a caramel. Add the butter and the cream to the pan, mix well and allow to cool.
To assemble: pipe the chestnut cream on to 12 of the pastry rectangles. Layer the pastry sheets on top of each other and then top with a 3rd sheet of pastry.
Serve with the caramel sauce.
«Try replacing the chestnut cream with pistachio paste and adding fresh raspberries.»