It is easiest to prepare this cake in what is known as a blender, i.e. a puree mixer.
Preheat the oven to 160 ° C. Grease a 24 or 26 springform pan or a loaf pan and sprinkle with flour.
Beat sugar, oil and eggs in a blender for 1 minute. Add baking powder, baking soda and half of the flour and beat again for 1 minute. Now add the ripe bananas, orange oil and the rest of the flour and beat for 3 minutes. Now stir in the very roughly chopped (only chop 2 - 3 times) walnuts.
Put the dough in the baking pan and bake for approx. 60 - 70 minutes, in the loaf pan possibly up to 90 minutes. Then cover with aluminum foil after 60 minutes. Make a stick test and bake longer if necessary.
Tips:
This cake has to bake long enough for it to develop the right flavor. It gets pretty dark.
The bananas should definitely be very, very ripe, i.e. overripe and definitely have brown spots on the skin.
If you use tartar baking powder, you need 2 teaspoons instead of one.