Put the flour, sugar, vanilla sugar, and milk into a bowl, sprinkle the yeast on top and wait a few minutes. Then start mixing the dough at slow and add the egg and (optional) butter. Also add the pinch of salt.
250 g Flour, 7 g Yeast, 125 ml Milk, lukewarm, 25 g Sugar, ½ tsp vanilla paste, 1 Egg, 50 g Butter, 1 pinch Salt
Mix quickly, the cover, and set aside to proof for about 40 - 60 minutes or until the dough has almost doubled in size.
Make the Short Dough
Put all ingredients for the pastry dough into a bowl and mix until everything is combined. Use your hands to press and shape the dough into a sphere.Put into the fridge for at least 20 minutes.
150 g Flour, 75 g Butter, 40 g Sugar, ½ tsp Vanilla Paste, 1 pinch Salt
Prepare the Filling
Chop the Walnuts.
100 g Walnuts
Remove the skin and core from the apples. Cut into thinner wedges and mix with some lemon juice to keep them from getting brown.
2 kg Apples, 1 Lemon
Pour the sugar into a pan and heat until the sugar is melting and becomes liquid.
175 g Sugar
Add the butter.
50 g Butter
Add the apple wedges and the walnuts to the pan and cook for 5 minutes.
Assemble The Cake
Preheat the oven to 175°C / 350°F (regular oven) or 150°C / 300°F (convection oven).
Use the yeast dough and the short dough and mix them together to become one dough. You might have to knead by hand at the end to combine it better and become smooth.
Use ⅔ of that dough and roll it out about 11 inch (for a 9-10 inch baking pan).
Put the rolled dough into a greased baking pan, making sure the rim is evenly covered with dough.
Put the filling into the pan and flip the sides over (onto the filling) where it is higher than the filling. Then roll out the remaining ⅓ of the dough at the size of your cake (just a bit larger) and cover the cake.
Use some leftover dough for decoration.
Bake for about 45 minutes to 1 hour, then take it out of the oven and let cool completely.
Glazing the Cake
Mix the confectioners sugar with the lemon juice, pour it over the cake, and using a pastry brush, even out the glaze. Let it dry.
100 g Confectioners Sugar, 1-2 tbsp Lemon Juice
Notes
Freezing this Cake
I was freezing half of this cake and it freezes and thaws well, however, the filling becomes a bit watery and is losing its caramel properties after thawing. I recommend enjoying this cake without freezing and it will be good in the fridge for several days.