Sounds strange I know, but I just made these and they are sooooo delicious!
1 can of black beans (drained and rinsed)
1 box of brownie mix
Drain the liquid from the beans and refill the can with water. put water and beans in blender and puree until smooth.
Mix this into the brownie mix and bake according to package directions.
No eggs or oil!
They are so fudgy and definitely don't taste like beans at all!