Put flour and cold fat in a mixing bowl. Add vinegar and 2 tablespoons of cold water and work vigorously with the dough hooks of the hand mixer. With cool hands quickly knead to a smooth dough.
Wrap in foil and refrigerate for about 45 minutes. For the choux pastry, boil 175 ml water, fat and salt. Add the flour at once and stir with a mixing spoon until the mixture comes off the bottom of the pot as a lump.
Put the dough into a mixing bowl. Stir in 1 egg immediately. Stir in the remaining eggs one after the other with a wooden spoon. The dough should fall off the spoon with a hard tear. Pour the choux pastry into a piping bag with a large perforated spout.
Roll out the short pastry to a rectangle (20 x 34 cm), cut in half lengthwise and lift onto a baking tray lined with baking paper. Spray the choux pastry onto the short pastry in waves, with 5 mm space between each wave.
Bake in the preheated oven (electric oven: 225 ° C/ gas: level 4) for 25-30 minutes. Do not open the oven during the first 20 minutes. Immediately after baking, cut the strips lengthwise in the choux pastry layer and let them cool on a cake rack.
Whip the cream until stiff, allow the vanillin sugar to trickle in little by little. Pour cream into a piping bag with a large star-shaped spout. Spread the lower choux pastry strips thickly with mixed apricot jam.
Spray cream on top. Place the choux pastry lid on the cream. Dust with icing sugar. Cut the strips into 4-5 cm wide pieces with an electric knife. Keep cool until serving.