Preheat the oven to 350°F. Line a loaf tin with parchment paper. 

In a large mixing bowl, whisk together the flaxseed meal and 4 tbsp water. Let sit for 2 minutes. Whisk in the vegetable oil, yogurt, vanilla extract, and sugars until creamy.

In a separate bowl, whisk together the flour, cocoa powder, espresso powder, baking powder and soda, and salt. Pour dry ingredients into wet and fold in using a spatula or wooden spoon until almost all the flour is gone. Fold in the shredded zucchini and chocolate chips until combined and no flour remains.

Pour batter into prepared loaf pan. (Optional) Sprinkle over some chopped dark chocolate. Bake for 50-60 minutes until a toothpick inserted comes out with a few moist crumbs, but no wet batter. Let the bread cool for 15 minutes before removing from the pan and slicing.

To Store: Wrap loaf tightly in plastic wrap or transfer to an airtight container. Store at room temperature for up to 3 days or at least a week in the fridge.