Preheat the oven to 350 degrees F. Grease a 9 X 9 inch square pan.
In a blender, puree the beans with the oil. Add the eggs, cocoa, sugar, coffee, and vanilla. Melt half the chocolate chips and add to the blender. Blend on medium-high until smooth In a small bowl, whisk together the flour, baking powder, and salt. Add to the blender and pulse until just incorporated. Pour into the prepared pan. Sprinkle the remaining chocolate chips and walnuts on top of batter. Bake until the surface looks somewhat matte around the edges and still somewhat shiny in the middle, about 20 minutes. Let cool at least 15 minutes before cutting and removing from the pan.
