Preheat oven to 350°F (175°C). Grease and flour two 8 1/2 x 4 1/2 inch loaf pans.

In a large bowl, whisk together flour, baking powder, baking soda, salt, and cinnamon.

In a separate bowl, beat eggs, brown sugar, and vanilla until well combined.

Stir in shredded zucchini and carrots into the wet ingredients.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix.

Stir in chopped pecans or walnuts and crushed bran flakes cereal.

Pour batter evenly into the prepared loaf pans.

Bake for 60 minutes, or until a wooden skewer inserted into the center comes out clean.

Let cool in pans for 10 minutes before transferring to a wire rack to cool completely.