Wash oranges hot, grate dry and finely grate the peel. Halve the oranges, squeeze the juice (there should be 150 ml). Separate the eggs. Beat egg white and salt until stiff
Mix the egg yolks, orange peel, orange juice, sugar, ricotta, sour cream and quark well with the whisks of the hand mixer. Stir in the polenta, fold in the beaten egg white. Pour the polenta cheese mixture into a greased springform pan (26 cm Ø) sprinkled with polenta, smooth it down and bake in a preheated oven (electric range: 175 °C/ convection oven: 150 °C/ gas: stage 2) for 1-1 1/4 hours
Let it rest for about 20 minutes with the oven door open. Remove and let cool on a cake rack. Roast the pine nuts in a pan without fat, remove. Dust the cake thickly with icing sugar and sprinkle with pine nuts
waiting time approx. 4 hours