Defrost puff pastry slices on a floured work surface next to each other at room temperature. Soak gelatine in cold water. Bring milk to the boil. Mix egg yolks, 60 g sugar and starch.
Add 50 ml milk, then pour back into the remaining milk. Bring the milk mixture to the boil briefly while stirring continuously and let it simmer for about 1 minute while stirring. Remove the pot from the heat and let it cool down for about 15 minutes.
Squeeze out the gelatine, stir in and cover the surface with foil. Allow the cream to cool, then chill after about 30 minutes.
Sprinkle each slice of puff pastry with 1 level teaspoon of sugar, then place on top of each other. Roll out the puff pastry rectangularly (approx. 18 x 30 cm) on a floured work surface and place on baking paper.
Chill the dough for about 30 minutes.
Place the puff pastry with baking paper on a baking tray, cover with baking paper and weigh down with a 2nd tray. Bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for 15-18 minutes until golden brown.
Let the dough cool down.
Cut the puff pastry into 18 equally sized rectangular pieces (approx. 3 x 10 cm). Leave to cool. Puree 150 g raspberries and pass through a sieve. Stir the puree into the cream. Whip the cream until stiff and carefully fold into the raspberry cream.
Pour cream into a piping bag.
Spray the cream in small tuffs on 12 strips of puff pastry. Place 2 cream strips on top of each other and finish with the last strip without cream. Sprinkle with icing sugar and decorate with remaining raspberries.