Grind the walnuts in a blender. Separate the egg whites from the yolks.

Whip the egg whites with a mixer to stiff peaks, then, continuing to whip, gradually add the sugar and finally fold in the yolks in parts.

Turn off the mixer, sift in the flour, add the nuts, and fold quickly and gently.

Pour the batter into a 16 cm pan and bake for 30 minutes at 180°C. Let the finished sponge cool and remove it from the pan.

Whip the cream, sour cream, and condensed milk at medium speed until airy and thick.

Cut the sponge into two layers.

Turn the layers over and spread a thin layer of cream on the inside of each. Arrange banana slices on the first layer, spread a generous amount of cream on top, and add another layer of banana slices.

Close with the second layer, cream side down.

Use the remaining cream to smooth the top and sides of the cake.

Make drips with the chocolate topping and top with caramel popcorn. Let the cake sit for a couple of hours to soak. Enjoy!