Dissolve baking soda in sour cream and set aside for now.
Using a fork, mash softened butter, sugar, vanilla and salt in a large mixing bowl.
Add egg and mix to a homogeneous mixture.
Stir the sour cream and soda into the butter mixture.
Add flour in batches and knead briefly and quickly to form a soft dough.
Divide the dough into 10 equal pieces (in my case 79 - 80 g each) and cover and chill for 30 minutes.
First take a piece of dough out of the fridge, roll it in flour and roll it out on a sheet of baking paper as round, very thin and almost transparent as possible. Cut a Ø 24 cm circle out of it (e.g. using a cake ring) and place it and the cut-off pieces of dough together with baking paper on a baking sheet.
Pierce the round cake layer several times with a fork and bake it together with the scraps of dough in a preheated oven at 392 °F (200 °C) for approx. 6 minutes.
Take the remaining pieces of dough out of the fridge one by one, roll them out into a circle and bake them individually together with the scraps of dough in the same way as the first cake layer.
Leave the 10 cake layers and the pastry scraps to cool.
Then finely crumble the pastry scraps.