Step 1

Preheat oven to 350 degrees F, and oil a standard muffin pan or 9x5-inch loaf pan.

Step 2

After grating the zucchini, gently squeeze out the excess moisture. Set aside.

Step 3

In a large bowl sift together the flour, cocoa, salt, baking powder, baking soda, and spices, if using. *If using a whole-grain flour such as spelt, sifting might separate out some of the fiber; add it to the bowl. Whisk to fully combine all dry ingredients.

Step 4

In a medium bowl whisk together the sugar, milk, flax meal, vanilla, oil and vinegar.

Step 5

Pour wet ingredients into dry, and stir just until combined. Fold in the zucchini and walnuts. Scoop batter into the prepared pan, and sprinkle the top(s) with chopped dark chocolate, if using.

Step 6

Bake muffins for 18 to 20 minutes and a loaf for 50 minutes to 1 hour. The bread is done when the center is firm and a toothpick or knife inserted in the center comes out clean or with a few crumbs. Cool in the pan for about 10 minutes, then transfer to a cooling rack.