Preheat your oven to 350°F (180°C). Grease the loaf pan and set aside.
In a large mixing bowl, combine the mashed bananas, honey, maple syrup, eggs, and vanilla extract. Stir well to combine.
Add the whole wheat flour, rolled oats, baking powder, and salt to the wet mixture. Mix until just combined. Do not overmix.
Fold in the chopped walnuts.
Pour the batter into the prepared loaf pan and smooth out the top.
Bake for 50-60 minutes or until a toothpick inserted into the center comes out clean.
Remove from the oven and let cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.