In a large mixing bowl, put the quark, sugar, egg yolks, lemon juice, zest, vanilla sugar, vanilla pudding powder, and salt. Mix until combined and then, add the melted butter at the end.
Beat the egg whites separately, until stiff peaks. This will take about 5-7 minutes.
Using a spatula, carefully fold your eggs whites foam into the quark mixture until fully incorporated. Be patient.
Pour this into your springform pan and bake for 50 minutes, until the top gets lighly browned.
Turn off the oven, leave the cheesecake inside, and the door open. Let it cool for 15 minutes.
Gently remove the cheesecake from the oven. Don't forget to run a knife around the edge before opening the pan.
Let it cool at room temperature. Once completely cool, refrigerate for 2 hours.
Garnish with whipped cream and berries before serving and enjoy!