Preheat your oven to 350°F (175°C) and grease a 9x5-inch loaf pan.

In a large mixing bowl, combine all-purpose flour, baking soda, ground cinnamon, and salt. Whisk well.

In a separate bowl, mash the ripe bananas, then add grated apple, shredded carrots, vegetable oil, eggs, vanilla extract, granulated sugar, and brown sugar. Whisk until smooth.

Gently fold the dry ingredients into the wet ingredients until just mixed to avoid overmixing.

If adding walnuts, fold them into the batter.

Pour the batter into the prepared loaf pan and smooth the top.

Bake in the preheated oven for approximately 50 minutes, or until a toothpick comes out clean.

Let the bread cool in the pan for 10 minutes before transferring to a wire rack to cool completely.