Preheat oven to 350°F.
In the bowl of a food processor blend black beans, vanilla, maple syrup, and applesauce until smooth. This might take several minutes to get the beans all ground up. Scrape down the sides as necessary.
Add the espresso powder, cocoa powder, flax meal, baking powder and salt and process until combined and smooth. Scrape down the sides as necessary.
Remove the blade and set aside. Add the chocolate chips to the batter and gently stir to incorporate.
Pour batter into an 8x8 baking pan lined with parchment paper. (Overhang the parchment paper on both ends by a few inches. This is very important as the brownies will still be very soft when they come out of the oven and the parchment paper will allow you to take the whole square of brownies out of the pan with ease.)
Bake for 35 to 40 minutes. The top should be set, but the center will still be soft. A toothpick will not (and should not) come out clean.
Let cool in the pan for 10 to 15 minutes. Carefully lift them out of the pan by holding onto the parchment paper overhang. They will probably still be soft and "bend" a little. This is ok, just be careful not to pull up on the sides too hard and break them.
Let cool on a wire rack for another 20 to 30 minutes. The brownies should be firmer now, but still soft and fudgy. Carefully cut out into heart shapes or into bars.
Sprinkle with powdered sugar if desired.