Melt the butter. Mix 150 g flour, 75 g sugar and vanillin sugar in a bowl and add the warm butter at once. Knead into crumbles with the dough hooks of the hand mixer.
Set aside. For the quark oil dough, mix quark, milk, oil, 75 g sugar, salt and lemon flavouring in a bowl. Mix 300 g flour and baking powder, stir in a little and knead in the rest.
Roll out the dough to a rectangle (approx. 42 x 30 cm) on a floured work surface. Spread apple compote on the dough, leaving one narrow side approx. 5 cm wide uncoated. Sprinkle with 50 g almond slivers and roll up the dough from the uncoated narrow side.
Cut the roll into 8 slices and place the snails on two baking trays lined with baking paper. Press the snails a little bit flat and sprinkle them with crumbles and remaining almond slivers. Bake in the preheated oven (electric cooker: 200 °C/ gas: level 3) for 20-25 minutes.
Let the snails cool down and serve dusted with icing sugar.