Preheat the oven to 350°F. Lightly grease a 9x5-inch loaf pan or line it with parchment paper.

Shred the zucchini using the large holes of a box grater. Gently squeeze out some of the extra moisture so it is damp but not dripping.

In a medium bowl, whisk together the all-purpose flour, whole wheat flour, oats, baking soda, baking powder, cinnamon, and salt.

In a large bowl, whisk the eggs, honey, olive oil, Greek yogurt, and vanilla until smooth.

Fold the shredded zucchini into the wet mixture. Add the dry ingredients and stir gently just until combined.

Fold in the chopped walnuts without overmixing.

Transfer the batter to the prepared loaf pan and smooth the top.

Bake for 48 to 52 minutes, or until the loaf is golden brown and a tester inserted in the center comes out clean or with a few moist crumbs.

Cool in the pan for 15 minutes, then transfer to a wire rack to cool completely before slicing.