I tried this recipe at a heart care seminar, and surprisingly, the brownies were delicious. I'm not sure everyone would enjoy them knowing the secret ingredient. This is one of those recipes where full disclosure doesn't come until everyone is done eating.
Black Bean Brownies
1 box brownie mix
1 (15.5 oz) can black beans, drained and rinsed
1/2 cup water
Preheat the oven as brownie mix box directs. Place drained beans and water into a blender or food processor, and process until smooth. Combine this with the brownie mix (and omit the eggs, water and oil the box directions specifies). Pour into desired size pan sprayed with non-stick spray. Bake as directed on the package.