Preparation Steps

• Preheat the oven to 350°F (175°C). Line an 8x8-inch baking pan with parchment paper, leaving an overhang for easy removal.
• In a medium bowl, whisk together the flour, cocoa powder, salt, and baking powder until evenly combined.
• In a large mixing bowl, whisk the melted butter and sugar until smooth. Add the eggs one at a time, whisking well after each addition, then stir in the vanilla.
• Fold the dry ingredients into the wet mixture until just combined. Do not overmix.
• Gently fold in the mashed banana, chocolate chips, and chopped walnuts, saving a small handful of chips and nuts for the top.
• Pour the batter into the prepared pan and spread it evenly. Sprinkle the reserved chocolate chips and walnuts on top.
• Bake for 30 to 35 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs (avoid overbaking to keep them fudgy).
• Allow the brownies to cool completely in the pan on a wire rack, then lift out using the parchment overhang and cut into 12 squares. Serve at room temperature.