Wash the apples, rub dry and hollow out with a melon cutter or teaspoon, remove some pulp too, so that more cheesecake fits in (do not pierce the bottom of the apples, otherwise the mixture can run out). Put the prepared apples in a greased baking dish.
Preheat the oven to 200 ° C.
Mix the cream cheese with the quark, sugar and vanilla sugar, then stir in the egg and finally the flour. Pour the mixture into the apples and bake them in a preheated oven at 200 ° C for about 25-30 minutes.
In the meantime, puree the plums with a little juice from the glass to a thin sauce, season with cinnamon. Serve the finished apples hot with plum sauce and, if desired, with crumbled speculoos.
Tip: Add some real vanilla from the pod or a vanilla shaker to the mixture.