Line the baking pan with baking paper so that the paper is about 3 cm above the edge of the pan, as the cake will rise slightly over the edge when baking if you use a Ø 20 cm springform pan.
Beat eggs, sugar, vanilla sugar, lemon zest, lemon juice and salt in a large mixing bowl with a whisk until homogeneous.
Add quark and cream and mix again until homogeneous.
Add cornstarch and mix again briefly to a homogeneous quark mass.
Put the quark mixture into the baking pan and bake the cake in a preheated oven at 180 °C top and bottom heat for about 1 hour, covering it with baking paper after about 45 minutes to prevent it from burning. The cake is done baking when it is still a little wobbly in the middle.
Let the crustless cheesecake cool a bit in the baking pan, then take it out and let it cool completely until it is no longer wobbly in the middle. Dust it with powdered sugar before serving.
