Place the puff pastry slices next to each other and defrost. Bring 400 ml milk to the boil. Stir 50 ml milk, sugar and pudding powder until smooth. Remove the milk from the stove and stir in the pudding powder. Boil the pudding while stirring for about 1 minute, then pour into a bowl and cover the surface with cling film.
Put the pudding in a cool place. Mix egg yolk with cream. Place 2 slices of puff pastry on top of each other and roll out square (26 x 26 cm) on a floured work surface. Cut 8 triangles from each square and spread them on 2 baking trays lined with baking paper. Brush the triangles with egg yolk cream first, then prick them several times in the middle with a fork. Bake the trays one after the other in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 15 minutes and let them cool down. Stir the pudding until smooth and put 1-2 tablespoons in the middle of each piece. Wash and halve the apricots and remove the stones. Cut the apricot halves into thin slices. Halve blackberries if they are too big.
Bake the trays one after the other in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 15 minutes and let them cool down. Stir the pudding until smooth and put 1-2 tablespoons in the middle of each piece. Wash and halve the apricots and remove the stones. Cut the apricot halves into thin slices. Halve blackberries if they are too big. Cover particles with apricot slices and blackberries and chill for about 30 minutes. Heat the jam and brush the pieces with it just before serving and sprinkle with chopped pistachios
1 1/4 hours waiting time