Step-by-step preparation:
Preheat oven to 180°C (350°F). Grease and flour the 3 baking pans.
In a large bowl, combine the eggs, sugar, oil, and vanilla. Add the mashed banana and mix well.
Sift the flour, baking powder, baking soda, cinnamon, and salt. Add gradually with a spatula, without overmixing.
Add the chopped apples and chopped walnuts. Mix with folding movements until well distributed.
Divide the mixture evenly among the 3 baking pans. Decorate with walnuts on top (evenly distributed).
Bake for 35 to 45 minutes, depending on the size of the pan. Test with a toothpick: it should come out clean.
Let it rest in the pan for 10 minutes. Then carefully remove from the pan and let it cool on a wire rack.
