Preheat oven to 325 degrees. Line 36 mini muffin cups with paper liners.
Cut the butter into chunks and put it in a saucepan or in a microwave safe mixing bowl. Add the chopped unsweetened chocolate and melt together. If using a saucepan, melt over low heat. If using microwave, heat at 50% power and stir every 40 seconds or so. Add the cocoa powder and set aside.
In a food processor, puree the drained chickpeas, agave and salt until smooth. Add the eggs and vanilla and process until smooth. Combine the chickpea mixture and melted chocolate in a mixing bowl. Let cool if still warm, then stir in the chocolate chips.
Spoon batter into mini muffin cups dividing equally among the 36. Bake at 325 F for 20 minutes or until brownies appear set and a toothpick inserted comes out with moist crumbs rather than batter. Let cool completely.