For the base, knead the fat, sugar, flour and egg into a smooth dough. Cover and chill for about 1/2 hour. Dice marzipan finely and chop almonds coarsely. Mix both with pistachios.
Separate the eggs for the filling. Cream fat and sugar. Add orange juice, quark, egg yolk and semolina and mix. Beat the egg whites until stiff and fold into the quark mixture. Roll out the short pastry and put it into a greased springform pan (26 cm Ø).
Press up an approx. 1 cm high edge with your hand. Prick several times with a fork and spread the nut mixture on top. Peel the oranges, cut them into slices and put them upright on the edge. Pour in the quark mixture.
Bake in a preheated oven (electric: 200 °C/ gas: level 3) for 1-1 1/4 hours, cover after 30-40 minutes. Dust with icing sugar shortly before serving. Garnish with orange. There are 12-16 pieces.