Grease 8" x 8" baking dish, or 8" springform pan works also.
Put black beans in food processor with eggs and mix just until blended well (some bit and chunks are ok).
Dump black bean mixture into a large bowl.
Add remaining ingredients and stir well by hand until batter forms.
Pour batter into prepared baking dish and bake at 350* for 30 minutes or until toothpick comes out *almost* clean. A little bit gooey is ok. Oven does not need to be pre-heated.
Notes
If using dry beans, start with 1/2 heaping cup when dry, soak over night, and cook until soft. Make sure they are cool before beginning this recipe. If you're feeling ambitious, you can mash the beans with a fork instead of using a food processor and then add the remaining ingredients. If you like sweeter - definitely go with the chocolate chips over the cacao nibs. I like my dessert not TOO sweet, so I go with the nibs in mine which also adds a little bit of texture.....as do the walnuts.