For the puff pastry:
- Place the crème diplomate into a piping bag and pipe blobs on to eight of pastry rectangles, placing a few raspberries in the gaps. Layer four of the filled pastry rectangles on top of the other four to make two layers per person, then top with remaining pastry rectangles (three pastry rectangles altogether per person).
- Bring the dough together, then tip out on to a lightly floured surface and shape into a large rectangle.
- Roll the dough out using a rolling pin into a longer thinner rectangle, then fold a third of the dough to the centre, and fold the other third on top. Roll the pastry out again to the same proportions as before and fold again in the same way. Rotate the pastry a quarter turn and repeat the rolling and folding. Continue for another three more times, rotating a quarter turn each time. Wrap the pastry in cling film and place into the fridge to chill for at least two hours.
- Preheat the oven to 185 (165 fan) and line a large baking tray with parchment paper.
- Weigh out 320g puff pastry and freeze or chill the remaining pastry for another use.
- Dust the work surface with a little icing sugar and roll out the pastry to a large rectangle a little smaller than the baking tray. Place the pastry on the baking tray, dust a little more icing sugar on top, then place in the oven with a rack on top. This will stop the pastry from rising too much in the oven.
- Bake for 50-55 minutes, until deep golden brown. Remove from the oven, carefully transfer to a chopping board and cut the pastry into 12 rectangles (about 4cm x 10cm each). Set aside to cool.
For the vanilla crème diplomate:
- Bring the milk to a simmer in a medium saucepan with the vanilla seeds or extract. Meanwhile, put the gelatin into a bowl of cold water to soften.
- In a bowl, whisk the egg yolks, sugar and cornflour together until pale. Pour the hot milk over the egg mix, whisking all the time, then pour the mix back into the pan over a low to medium heat. Continue to whisk until the pastry cream starts to thicken and boil, then remove from the heat.
- Squeeze out the water from the gelatin and whisk into the hot mixture.
- Pour into a bowl and press a sheet of cling film on to the surface. Cool for 15 minutes before placing in the fridge to cool completely.
- Once completely cold, beat until smooth, then fold in the whipped cream.
- Crush the raspberries in a bowl with a fork then fold into the crème diplomate to make a ripple effect.
- Place the crème diplomate into a piping bag and pipe blobs on to eight of the pastry rectangles, placing a few raspberries in the gaps. Layer four of the filled pastry rectangles on top of the other four to make two layers per person, then top with remaining pastry rectangles (three pastry rectangles altogether per person).
- Dust with icing sugar and serve.