Butter round casserole.
Whisk eggs with sugar and vanilla sugar until fluffy. Add flour, salt, baking powder, quark and milk to egg mixture and stir well.
Rinse and pit cherries, halve and drain well.
Pour mixture into baking dish and spread cherries on top. Press cherries gently into batter.
Bake in preheated oven at 180°C (approximately 350°F) for about 30 minutes or until golden brown. Cool, sprinkle with powdered sugar and serve with whipped cream, if desired.