Adjust the oven rack to the lower third position and preheat oven to 425°F. Spray a 12-count muffin pan with nonstick spray or line with cupcake liners.
Using a box grater or a food processor shred the zucchini. Place shredded zucchini on a couple paper towels to absorb some (but not all) moisture. Press a paper towel on top as well.
In a large bowl, whisk flour, cocoa powder, baking soda, baking powder, salt, instant coffee and chocolate chips together until combined.
In a medium bowl, whisk eggs, oil, yogurt, sugar and vanilla together until combined.
Add wet ingredients to dry ingredients and lightly whisk until combined. Using a rubber spatula or wooden spoon, fold in the zucchini.
Spoon batter into prepared muffin pan filling each cupcake liner to the top with batter.
Bake for 5 minutes at 425°F. Lower temperature to 350°F and continue to bake muffins for 12 to 15 minutes longer or until a toothpick inserted in the center comes out clean.
Allow muffins to cool completely in the pan set on a wire rack.
Notes
* I used Cup4Cup gluten-free flour ("original flour blend"). * Not looking for a gluten-free dessert? Substitute regular all-purpose flour 1:1 for the gluten-free flour * Muffins freeze well. Make ahead and store for a few months in the freezer. * Instead of muffins you can bake this in a loaf pan at 350°F for 45 to 55 minutes.