Step 1

Preheat oven to 350°F. Line an 8-by-8-inch baking pan with parchment paper, with ends overhanging the sides. Spray lightly with cooking spray.

Step 2

In the top of a double boiler over barely simmering water, melt chocolate and butter until smooth. Meanwhile, in a food processor, puree black beans, sweet potato, egg, syrup, vanilla, baking powder, and salt. Add chocolate mixture and process until smooth.

Step 3

Pour batter into pan and bake until brownies set in the center and pull away from the edges, 40 to 45 minutes. Cool completely before using the parchment paper to remove brownies from the pan.