For the short pastry, knead flour, 50 g sugar, 1 pinch of salt, 150 g butter in pieces and 4-5 tbsp cold water first with the dough hooks of the mixer and then briefly with your hands until smooth. Cover and chill for about 30 minutes.
Grease a springform pan (26 cm Ø). Good 3⁄4 Roll out the dough on some flour round (about 34 cm Ø). Line the springform pan with the dough, pressing it down at the edge to a height of about 4 cm. Prick the bottom of the dough several times with a fork.
Chill the rest of the dough.
Grate the marzipan evenly on the dough base. Cream 100 g butter and 75 g sugar. Peel, quarter, core and roughly grate apples. Squeeze the grated apples with your hands and mix into the butter-sugar-cream.
Separate 1 egg. Beat 2 egg whites until stiff and fold into the apple mixture in portions. Spread into the mould.
Roll out the rest of the dough onto a little flour (approx. 27 cm Ø). Cut into strips (approx. 1 cm wide) with a dough wheel or knife. Place as a grid on the apple mixture, press lightly on the edge.
Whisk 1 egg yolk and condensed milk. Brush the grid with it. Bake the cake in the preheated oven (electric oven: 175 °C/circulating air: 150 °C/gas: see manufacturer) for approx. 55 minutes (if necessary, cover with aluminium foil after approx. 45 minutes).
Let it cool down in the springform pan.