Actually Good Black Bean Brownies

Name: Actually Good Black Bean Brownies
Ingredients: Baking spray or neutral oil, for greasing the pan; 1 (15.5-ounce) can black beans, rinsed and drained; 3/4 cup (202 grams) smooth sunflower seed, almond, or peanut butter; 1/2 cup (127 grams) unsweetened applesauce; 1/4 cup (78 grams) maple syrup; 1 1/2 teaspoons vanilla extract; 1/2 cup plus 3 tablespoons (64 grams) unsweetened cocoa powder; 1 teaspoon baking powder; 1/2 teaspoon kosher salt; 1/2 cup (85 grams) semisweet chocolate, coarsely chopped, divided; 1/2 cup (81 grams) salted roasted nuts, such as almonds, peanuts, walnuts, or hazelnuts, coarsely chopped (optional); Flaky sea salt