The surprise? Pureed black beans replace some of the butter, cutting the fat from 11g to only 7g!
1/4 cup (1/2 stick) unsalted butter, plus more for pan
1/4 cup black beans, rinsed, drained, and pureed until completely smooth
3 ounces semisweet chocolate, chopped (1/2 cup)
2 ounces unsweetened chocolate, chopped (1/3 cup)
1 and 1/3 cups sugar
2 large eggs, plus 1 large egg white
1 and 1/2 teaspoons pure vanilla extract
1 cup all-purpose flour
1/4 cup unsweetened cocoa powder
1/2 teaspoon baking powder
1/2 teaspoon salt
Preheat oven to 350 degrees. Lightly butter a 9-inch square baking pan and line with parchment paper, leaving a 2-inch overhang on all sides. In a large microwave-safe bowl, combine butter, bean puree, and chocolates and microwave in 30-second increments, stirring each time, until melted and smooth, about 2 minutes. Whisk in sugar, eggs and egg white, and vanilla until smooth.
In a small bowl, whisk together flour, cocoa powder, baking powder, and salt. Stir into chocolate mixture until just combined. Pour batter into pan; smooth top. Bake until top is cracked and toothpick inserted in center has moist crumbs attached, about 25 minutes (center will seem undercooked but will set further as it cools). Let cool completely in pan on a wire rack.
Using parchment, lift brownie from pan and cut into 16 squares.