Preheat oven to 350 degrees. Grease four mini loaf pans with nonstick baking spray.
In a large bowl, whisk together oil, granulated sugar, brown sugar, eggs, milk, vanilla extract, and coffee extract until smooth and creamy.
In another bowl, mix together flour, cocoa, salt, and baking soda.
Add the flour mixture to the wet ingredients and stir until just combined. Add grated zucchini and chocolate chips and fold until evenly incorporated throughout the batter.
Divide the batter evenly between the four loaf pans. Bake at 350 degrees for 30-35 minutes, or until a toothpick inserted into the center of each loaf comes out cleanly. Remove the bread from the oven and allow to cool in the pan for 10 minutes before turning out each loaf onto a cooling rack.
When completely cooled, dust each loaf with powdered sugar if desired, and store in an airtight container.