This cake originated in Kiev, Ukraine, back in 1950's. Over the years it has gotten popular and now boasts a top choice among the favorite dishes of Ukraine, just like its few other siblings, Pelmeni and Poppy Seed Buns.
Prepare an 11 inch Sponge cake based on the recipe link above.
Whip egg whites until they are doubled in volume, add sugar.
Whip until it becomes thick, just like in the picture.
Using a spatula, mix in the hazelnuts, stirring in a circular motion, lightly mixing the ingredients.
Place the mixture into an 11 inch baking sheet, lined with parchment paper. Bake it at 250F for 6 hours.
Beat egg yolks, add water and condensed milk. Stir until smooth.
Cook all ingredients on a very low heat. Continue mixing the cream; mix it the entire time as it sits on the heat. Make sure that nothing is being stuck on the corners. During this processes, keep adding the heat by a bit. Make sure not to bring your mixture to boil. Keep on mixing and cooking, until mixture has the texture of the condensed milk.
Remove the mixture form the heat and while it’s hot, add chocolate to it. Give it a few minutes to melt and mix it through. Let the mixture cool off to a room temperature.
In a separate bowl, mix butter; add the cream mixture a few spoons at a time, until it's mixed well.
Splice the cake horizontally, as thin as you can, into several layers. Cover each layer with jam, excluding the top layer.
Begin layering the cake by covering the bottom layer of Sponge Cake with cream; followed by meringue; followed by cream, again.
Cover the cake with the remaining layers of Sponge Cake. Once the cake is put together, dress it up with the remaining cream and your choice of decoration.