30 minutes before preparing the cakes, place the butter in the freezer. Grate the frozen butter on a coarse grater into the dough bowl. Sprinkle the grated butter with flour to prevent it from sticking. Preheat the oven to 190°C.
Prepare the dough: quickly grind the flour and butter into crumbs. Then add sour cream, egg and soda slaked with vinegar.
Knead the dough. As soon as it comes together, put it in a bag and put it in the refrigerator for 1 hour.
Prepare the cream: combine eggs, flour, vanillin, a little milk and mix everything thoroughly until smooth. Separately, bring the milk and sugar to a boil. Stirring constantly, add hot milk to the egg mixture. Mix well and return the whole mass to the fire.
Over medium heat, bring the cream to thicken, stirring constantly. Cover the finished cream with film and cool completely.
Divide the dough into 8 parts.
Spread the finished cakes with the cooled custard.
Grind any excess into crumbs.
Coat the top and sides of the cake with cream and sprinkle with crumbs, then refrigerate overnight, or better yet, overnight.
Serve the cake by cutting into portions.