Heat the oven to 329°F (165 °C). Prepare 2 flat trays and 8 sheets of baking paper the size of the inverted trays. Use a mixer only.
Pour the flour, baking powder and sugar in the mixer's bowl and mix. Add the diced butter, 2 eggs, sour cream, vanilla and mix on low speed until the ingredients are well mixed and form into a ball of dough.
Take it off the mixer, cover with foil and leave in the fridge for about 1 hour. After that, divide it up into 8 equal parts, roll out each part into a very thin rectangular sheet onto floured baking paper. Transfer it with the baking paper to the tray that you've placed upside down in the oven.
Bake at 329°F (165 °C) for about 5-7 min. until the edges start to brown. Take it out of the oven and leave it aside. Proceed in the same manner with the other parts of dough. It's easier to work with 2 trays. You can put the ready layers on top of one another with the baking paper. Let them cool.
Dissolve the starch in 1 cup of cold milk. Heat the rest of it on a moderate stove with the sugar. Add the dissolved starch to it and cook to a thick cream. Remove from the stove and add the chocolate, stir until it melts. Cover with foil and leave to cool completely. Once it is, beat the butter with a mixer and add the cream to it spoon by spoon. Finally, add the vanilla.
Place 1 cake layer in a suitable form/platter and smear it with 5-6 tbsp cream. Place a 2nd layer on top and smear with cream. Repeat until you've placed the last layer, which you can also smear with cream if there's any left. Smooth it out and let cool.
Melt the chocolate and butter in a water bath. Let cool to room temperature and pour it over the cake. Smooth it out.
Leave the cake in the fridge for 24 hours, then cut it with a wide, flat knife into small rectangular pieces.
Source: Ossigeno culinary blog.
Notes: I can't pinpoint the true source of this cake recipe, unfortunately. I've seen it listed as Croatian, Serbian and Hungarian. Looks like every one of these countries has their own claim on it.
In many of the videos I saw the Serbian women use margarine for the cake layers, dough and cream, which was something incomprehensible to me. I used butter as shown in Ossigeno's culinary blog.
The quantities listed are quite a lot, so feel free to cut them in half.
I used a digital scale to divide up the dough into 8 equal parts. First I weighed all of the dough and then divided into 8 to obtain the exact amount for each layer.
The cake is a delightful one, easy to make and suitable for an afternoon coffee.