Mix the flour, yeast, sugar, egg, lukewarm water, soft butter, and butter-vanilla flavor to form a dough. Let rise for 30 minutes until roughly doubled in size.
Peel, core, and cut the apples into small cubes. Simmer with roughly 150ml water and vanilla sugar over medium heat for 8-10 minutes until soft. Add cinnamon to taste if desired. Drain the apples, keeping the cooking liquid.
Bring the apple cooking liquid to a boil. Mix the pudding powder with roughly 100ml water or apple juice until smooth, then stir into the boiling liquid to thicken. Remove from heat and let cool completely.
Fold the sour cream into the cooled pudding. Add the cooked apple pieces and almond leaves, then mix well.
Roll out the dough very thinly and cut out 8 circles. Place the apple mixture in the center of each circle, fold the dough over at the edge, and press firmly with a fork to seal.
Prepare the crumble topping ingredients and spread evenly on top of each turnover. Bake in a preheated oven at 200°C (390°F) for 25 minutes until golden brown.