So, start with the cream: beat well the condensed milk with the softened butter. And put into the fridge.

Then make the biscuit cake. To do this, proteins separated from the yolks. Whisk yolks well with sugar.

After, add the flour, baking powder and cocoa and again beat well until smooth. Here you can taste and, if you really have a sweet tooth, add sugar a little more. But I arranged everything and so.

Separately whisk the whites (I always add a bit of sugar proteins, regardless of whether there is sugar mixed in the dough or used to have)to firm peaks. And added to the batter. Gently stir until smooth.

Split form (I have a form with a diameter of 24 cm) lay a parchment or cling foil, grease with oil and pour the prepared dough. Bake at t180*, about 30-40 minutes. But the best readiness check wand.

The finished cake, still hot, fold in half, but in the middle to put the rolling pin (as pictured). And so leave to cool. Foil or paper to remove.

Next, take the buttercream out of the fridge, it needs a good freeze, if this has not happened for some reason (the cream turned watery), then add more butter (whisk and put back in the fridge). Unfortunately I had the story, but..... butter is no longer found, so the cream was a bit watery, but..... eating cake, taste is not affected. Remove the rolling pin from the cake, fill the void with half of the cream in the center put a peeled banana (it took me one banana, because he was big), and on top of the other half of the cream.

The top of the cake (or rather his side) grease with any cream or icing (but preferably the glaze and the cream take). I used protein custard cream from here http://www.povarenok.ru/recipes/show/15634/ (not for 5 proteins and 2, and the cream I have left).

Top cream (or frosting) sprinkle any ground nuts. Put the cake in the refrigerator for impregnation. I stand the whole night.

So cake looks in the cut (but again, a little summed up the cream).