In a large mixing bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, cinnamon, espresso powder, and salt.

In a medium mixing bowl, whisk together the melted butter, oil, eggs, and vanilla. Add to the flour mixture, along with the zucchini and chocolate chips. Stir together until combined. (The batter will be very thick.) Scoop the batter into the prepared pan and spread it into an even layer.

Let cool in the pan on a wire rack for 20 minutes. Remove the bread and cool completely on the rack or until slightly warm before slicing and serving. The bread can be wrapped and stored at room temperature for up to 4 days. Individually wrapped slices freeze well, too!