Warm the milk in a pot lukewarm, remove from the stove. Dissolve yeast in it. Put flour, butter, 1 egg, 1 tablespoon stevia and a pinch of salt in a bowl. Add the yeast milk, first with the dough hooks of the hand mixer, then knead with floured hands to a smooth dough. Cover and leave to rise in a warm place for about 30 minutes
In the meantime, mix sour cream, 2 eggs, 3 level tablespoons of Stevia, lemon zest and 1 pinch of salt. Sprinkle with sauce powder and stir in. Knead the dough again, roll it out on a floured work surface, place it in a greased baking tin (approx. 24 cm Ø) and press it down lightly
Spread the cheese mixture on the dough. Peel and quarter the apple and remove the core. Cut the apple into thin slices and cover the cake with them. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 45 minutes (cover after approx. 30 minutes if necessary), remove. Bring jam to the boil with 1 tablespoon of water in a pot, brush the cake with it, let it cool down on a cake rack for about 1 hour