Sieve wheat flour, baking powder and baking soda together. Keep it aside.
In a grinder jar take oil and sugar and churn for 10 to 15 seconds
Put all the eggs in the grinder and churn for a minute.
Add vanilla essence and churn to mix.
Take the mixture out in a mixing bowl.
Add the wheat flour mixture and mix with a wooden spoon till well mixed.
Mix bananas and walnuts into the above mixture. The mixture will be quite thick as compared to normal cake mixture.
Transfer to a oiled and dusted(with wheat flour) loaf tin.
Level with a spoon and bake in a pre heated oven at 180º C for 50 to 55 minutes.
Check the done-ness with the help of a skewer.
If the skewer or knife inserted comes out clean, the cake is ready.
Cut into slices. Tastes best when eaten warm.
After first 20 minutes of baking, switch off the upper heater road of the oven.