Using the hand mixer, stir 2 eggs with the sugar and vanilla sugar until frothy. Carefully stir in 2 tablespoons of cornstarch and the grated zest of the lemon. Add 500 g low-fat quark (if possible dry, let drain) and 100 g low-fat yoghurt, stir to a smooth cream. Stir in the raisins. Beat 4 egg whites with a pinch of salt until very stiff. Fold the egg whites under the mass.
Line a springform pan with baking paper. Pour the cake mixture into the mold. Bake in a preheated oven at 160 ° C for 50 to 55 minutes.
Put the cooled cake on a plate and dust with powdered sugar.