Sift the icing sugar. Cream 170 g butter, vanilla flavouring and 80 g icing sugar with the whisk of the hand mixer. Mix flour and starch and stir in. Wrap the dough in foil and chill for about 1 hour. For the filling, whisk 80 g butter with the whisk of the hand mixer until creamy, stir in 120 g icing sugar. Cut open the passion fruit, scrape out the pulp with a teaspoon and stir into the butter. Put the filling in a cool place.
Shape dough into rolls (5 cm Ø) and refrigerate for about 30 minutes. Cut dough rolls into approx. 0.5 cm wide slices and place them on 2-3 baking trays lined with baking paper. Dip the fork repeatedly in flour and press the cookies a little flat with it. Bake the trays one after the other in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 10 minutes. Let the cookies cool down for about 30 minutes. Spread the filling with 2 teaspoons on the underside of half of the biscuits and place the remaining biscuits on top
waiting time approx. 1 3/4 hours