For the banana oat cake, mash the bananas with the fruit juice. Beat the eggs with the powdered sugar in a food processor until foamy, at least 10 minutes.
Mix the flour with the baking powder and then with the nuts. Preheat oven to 160°C hot air. Slowly beat into the egg mixture the fruit mixture, oil and flour mixture alternately (thirds).
Grease a large loaf pan and dust with flour, pour in the mixture. In the preheated oven, the banana-oat cake needs about an hour.