Knead 250 g flour, 50 g sugar, 1 pinch of salt, butter in pieces and egg first with a hand mixer and then briefly with your hands until smooth. Chill for about 1 hour.
Grease rectangular (20 x 29 cm) or round (28 cm Ø) tartlets with a removable bottom. Roll out short pastry on some flour rectangular (approx. 24 x 33 cm) or round (approx. 32 cm Ø).
Line a tart mould with it, pressing the edges into the grooves. Prick the pastry base several times with a fork.
Place a large piece of baking paper on the dough. Fill with dried peas. Bake the tart in the preheated oven (electric oven: 200°C/circulating air: 175°C/gas: level 3) for about 25 minutes. Remove the baking paper together with the dried peas.
Let the tart cool down in the mould.
Mix 100 ml milk, pudding powder and 50 g sugar. Boil up the rest of the milk, stir in the pudding powder. Bring to the boil again and simmer for about 1 minute while stirring. Stir in almonds. Let it cool down, stirring more often.
Stir together the sour cream and cream setting agent. Immediately fold into the pudding. Spread into the tart. Chill for about 1 hour.
Pick the berries, wash them. Mix casting powder and 2 tablespoons of sugar. Stir in 1/4 l water. Boil up while stirring. Fold in berries. Spread on the tart. Chill for about 30 minutes.