Preheat your oven to 325°F. Line an 8-inch square baking pan with unbleached parchment paper or nonstick aluminum foil, and set it aside. In a blender or food processor, place the drained and rinsed beans and eggs, and blend until very smooth. Set the mixture aside.
In a large bowl, place the brown sugar, nonfat dry milk, cornstarch, baking powder, and salt, and whisk to combine, breaking up any lumps in the brown sugar.
To the large bowl, add the beans mixture, butter, and vanilla, and mix until very well-combined. If necessary, whisk vigorously to smooth the mixture, which will be relatively thin.
Transfer the mixture to the prepared pan and scatter about half of the chocolate chips gently on top of the batter. They will sink a bit during baking, but shouldn’t fall all the way to the bottom.
Place the baking pan in the center of the preheated oven and bake for 15 minutes.
Open the oven door, gently pull out the rack with the pan on it, and scatter the remaining chocolate chips evenly on top of the blondies as they are baking. Return the rack with the pan on it to the oven, close the door, and continue baking for another 15 to 20 minutes, or until the top is lightly golden brown all over and the blondies spring back when pressed gently in the center.
Remove the pan from the oven and allow to cool for at least 10 minutes before transferring the blondies, still in the paper or foil, to a wire rack to cool completely.
Slice into 9 equal pieces, and serve. Store any leftovers in a tightly sealed container in the refrigerator for up to 1 week, or in the freezer for longer storage.