from Spilling the Beans: Cooking and Baking with Beans and Grains Every Day by Julie Van Rosendaal and Sue Duncan
I have no idea if the black beans do anything or just make you think what you're eating is healthy, but in any case, these are the best brownies I've ever had.
Also, I suggest sifting the flour. I learned this from Beareen and it makes such a difference.
1 cup cooked black beans (dry them off if wet)
1 1/4 cup pecans
1/2 cup butter
2 oz unsweetened chocolate
1/3 cup flour
pinch of salt
3/4 cups sugar
1 tsp vanilla
2/3 cup chocolate chips OR 100 g of bittersweet or semi-sweet dark chocolate
Preheat to 350F. Toast nuts until fragrant and very lightly browned, about 6 minutes.
In a small saucepan over very low heat, melt butter and unsweetened chocolate, taking care not to let the mixture scorch. Whisk to combine, then remove from heat and let cool for a few minutes.
In a medium bowl, whisk together flour and salt.
Place beans and the butter/chocolate mixture in bowl and process until very smooth. Add eggs, sugar, and vanilla; process until combined. Scrape the mixture into the flour mixture and fold gently, leaving streaks of flour still visible. Add the nuts and chocolate chips and fold until just combined.
Pour the batter into a lightly buttered 8'' square pan. Bake for 30 minutes, or until the batter doesn't jiggle but any toothpick inserted would still be chocolatey.