Preheat oven to 350˚F/177˚C.
Lightly butter and line a 9"x9" square baking pan with parchment paper.
Into the bowl of a food processor add zucchini, butter, eggs, and vanilla extract. Pulse until completely smooth, scraping down the sides to make sure that there are no chunks of zucchini.
Add to the puree, baking powder, espresso powder, salt, flour, cocoa powder, and sugar. Pulse until just combined.
Add the chocolate chips and pulse a few times to break the chocolate up slightly.
Pour the batter into the prepared pan.
Bake for 25-30 minutes or until a toothpick inserted comes out with wet crumbs.