Preheat the oven to 180°C.
Beat the eggs with a fork, then whisk in the oil and vanilla.
In a large mix the sugar, flour, baking powder and salt, then add the egg mixture. Stir until combined.
Fold in the mashed bananas, then add the walnut pieces.
Line the base and grease the sides of a non- spring form cake tin.
Pour in the mixture and bake in the preheated oven for about 35-40 minutes.
Do a skewer test and, when the cakes is cooked through, remove it from the oven and let it rest in the tin for ten minutes, then release the spring form tin and leave it to cool completely.