Knead flour, 75 g sugar, vanillin sugar, salt, 1 egg, almonds and butter in cubes with the dough hooks of the hand mixer. Then work again with your hands to a smooth dough.
Roll out the dough into a circle (approx. 28 cm Ø) on a floured work surface. Place in a greased, flour-spread tart mould with lift-off base (26 cm Ø; with wavy rim). Press the edge lightly and chill for about 30 minutes.
In the meantime, stir the sour cream, 75 sugar, 3 eggs and sauce powder with the whisk of the hand mixer until smooth. Wash apples thoroughly and remove the core with a core cutter. Cut apples into rings of approx. 2 cm thickness.
Roll out marzipan into a circle (approx. 26 cm Ø) on a work surface lightly dusted with icing sugar. Place on the tart base and spread apple rings on top. Sprinkle with almond flakes and pour the icing evenly over it.
Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) on the lower rack for approx. 50 minutes. Remove from the oven, place on a rack and allow to cool. Dust with icing sugar.