I love these brownies. They may have a little different texture than you are used to, but you can not taste the black beans at all.
There is absolutely no flour in these brownies, which makes them gluten free.

You will need an 8″ square pan, greased
Preheat your oven to 350 degrees Fahrenheit/175 Celsius
You will also need a food processor for mixing.

3/4 cup dry black beans
water, for cooking the beans
3 eggs
1/3 cup melted organic, virgin coconut oil OR butter
1/4 heaping cup cocoa powder
2 teaspoons vanilla extract
1/2 cup + 2 Tablespoons sugar
1 cup semi-sweet chocolate chips

Rinse the black beans and cover with water. Bring to a boil, cover with lid left ajar and took until beans are soft. This takes about an hour to an hour and a half.
When done, drain. You should have 1-1/2 cups cooked beans. If you have more than that, set those aside for something else.
Put the blade in your food processor. Add the drained beans. Or you can drain and rinse a 15 oz. can of black beans and add those to the food processor bowl.
Add the cocoa powder, coconut oil ,eggs, vanilla extract, and sugar.
Put the cover on the processor and turn on, blending until smooth.
Take off the lid and stir in the chocolate chips.
Scrape the batter into the greased pan and spread evenly.
Bake for 30 minutes or until the brownies test done when poked with toothpick.
They may just start to pull away from the sides.
Take out of oven and let cool.

I usually get 16 brownies out of a pan. They are pretty filling.

I like coconut oil better in these brownies. However, butter is more economical and tastes pretty good too.