Preheat oven to 350 degrees F (180 degrees F). Grease an 8-inch square pan with cooking spray.
In a large mixing bowl, whisk together the pureed avocado and olive oil until smooth. Add in the flour, cocoa powder, sugar, baking soda, salt, and water (or coffee + water). Stir until smooth. Fold in 1 cup of the chocolate chips.
Pour into the prepared pan and spread the batter evenly throughout the pan. Sprinkle with an additional 1/2 cup of dark chocolate chips on top. Bake for 15-20 minutes, or until a toothpick inserted into the center comes out mostly clean (there may be some melted chocolate chips in there). If you overbake, the brownies will have a cake-like texture.
Remove and let the brownies sit out for at least 20 minutes before serving. Cut and serve, or cover and store for up to 3 days.