Place the cornflour in a pan and slowly whisk in the milk to avoid any lumps.

Next whisk in the cream, caster sugar and vanilla paste.

Place the pan over a medium heat and whisk continuously until it just begins to thicken.

keep whisking until it starts to bubble and boil.

Remove from the heat, add the butter and whisk until the butter has melted and fully combined with the rest of the crème pâtissière mix.

Scrape the crème pâtissière into a bowl and cover with clingfilm that is directly touching the surface (to avoid a skin forming).

Place into the fridge until ready to use.

Preheat the oven to 200C / 392F / gas mark 6.

Roll out the puff pastry sheet on to a baking tray lined with baking paper.

Cut into 12 equal rectangles.

Top with a sheet of baking paper then place a second baking sheet over the top of the pastry.

Bake for 15-20 minutes or until golden brown and crisp.

Remove from the oven and place on a cooling rack.

Remove the crème pâtissière from the fridge and whisk until fluffy and smooth.

Put the crème pâtissière in a piping bag and pipe onto 8 of the 12 puff pastry rectangles.

In a small bowl, mix together the icing sugar and water until smooth and spreadable.

Melt the dark chocolate and add to another piping bag.

Pipe 3 thin lines of dark chocolate on top of the icing and then, using a skewer, create a feathered pattern by dragging the skewer back and forth through the chocolate and icing.

Stack 2 of the puff pastry sheets topped with crème pâtissière and one of the puff pastry sheets that has been decorated and serve.