I searched Google and found several references and pieced together this recipe.
1 box Brownie mix (9x13 pan size)
1 can black beans (15 ounce size)
Drain and rinse the beans and the can thoroughly.
Put the beans back in the can.
Fill can to top with water.
Dump beans and water into blender or food processor. (I used the food processor)
Whir them around till they no longer look like beans. They look sort of like chocolate cake batter at this point with flecks of darker chocolate.
Dump the bean mush into a bowl with the brownie mix and stir it up.
Pour it into a 9x13 pan that has just the bottom greased. Bake it according to the directions on the box.
Mine were done at the long end of the bake time. My box said 28-32 minutes and 32 was about right.
Leave a bit of batter in the bowl to lick.This recipe uses no eggs so reward yourself!
As you can see in the picture I did not wait for them to cool before topping with ice cream and sampling.
I could not tell there were beans in it. The batter and the finished brownies tasted of nothing but chocolate.
The brownies did not rise as much as I am used to. They stayed flat.
The brownies were very rich and dense. They were almost too sticky. The flavor is fine. It is the texture that I did not like as well.
I think I will try them once more, but bake them in a square pan and perhaps add some walnuts.
I do prefer my other brownie recipe where I simply replace the oil with applesauce and follow the rest of the directions exactly.