Mix the fat with sugar until frothy. Gradually stir in the egg yolks, lemon juice and zest, flour and quark carefully. Finally, carefully fold in the egg whites and add raisins if you like.
Bake in a greased springform pan (26 cm diameter) dusted with flour at 170 ° C on the second rack from below for 60 - 90 minutes. If necessary, cover with parchment paper towards the end of the baking time so that the cake does not get too dark.