Orange Cheesecake with Polenta

Separate the eggs. Beat whites with salt until stiff. Gradually add  5 tablespoons sugar and beat to stiff peaks. Rinse the orange in hot water and wipe dry, then finely grate the zest. Beat the egg yolks with the remaining sugar and the orange zest until fluffy. Mix cornmeal and baking powder with the quark, mascarpone and crème fraiche until smooth, then carefully fold in the beaten egg whites and spread mixture on the prepared baking sheet. Sprinkle with pine nuts and bake for 30-35 minutes. About 10 minutes before end of baking, sprinkle with some sanding sugar to produce a caramelized top. Remove cake from ovenand let cool completely. Just before serving, dust with powdered sugar.