Mix the flours, salt, vanilla sugar if using, baking powder and/or soda, cinnamon powder together
Mash the banana's with a fork
Mix the sugar and the butter and beat the mixture until creamy
Add the eggs to this sugar/butter mixture and mix briefly
Then add the pureed bananas to the above and the yoghurt and mix. When using add more yoghurt or buttermilk in this step
Subsequently add the dry pre-mix and carefully mix, until the flour mixture is well mixed and has absorbed the moisture.
Finalize with adding the partially broken walnuts
Let the mixture stand for 15 minutes and pre-heat the oven till 350 F (180 C)
Then butter the cake or pie form with some butter or vegetable oil
Fill the form with the banana dough and place in the middle of the oven
Check color after 40 min and the target cooking time is 45-50 minutes
Take the cake out when done and let it cool down. In dry environments, you can cover with a piece of parchment paper, but do not close it off completely.