Step 1

Preheat oven to 325°F.

Step 2

Spray two 8 1/2-by-4 1/2-inch loaf pans with cooking spray.

Step 3

Whisk all-purpose flour, whole-wheat flour, cocoa, baking powder, baking soda and salt in a large bowl.

Step 4

Whisk eggs, sugar, applesauce, oil, vanilla and melted chocolate in another large bowl until blended.

Step 5

Add the dry ingredients and stir with a rubber spatula until just combined.

Step 6

Fold in zucchini and walnuts.

Step 7

Pour the batter into the prepared pans. Bake the loaves 55 to 60 minutes, or until a toothpick inserted in the center comes out clean.

Step 8

Let cool for 10 minutes. Invert onto rack and cool completely.