Combine the black beans, eggs, oil, cocoa powder, baking powder, salt, vanilla, and sugar in a blender. Blend until smooth. Pour the mixture into the prepared baking dish. Sprinkle the chocolate chips over the mixture or mix into the batter.
Bake in a preheated oven until the top is dry and edges start to pull away from the sides of the pan, about 30 minutes.
I frost them by putting the remaining bag of chocolate chips on top of the brownies when they come out of the oven. When melted, I spread them around.