01 - Preheat oven to 350°F. Line an 8x8-inch baking pan with parchment paper.
02 - In a medium bowl, whisk together flour, cocoa powder, baking powder, and salt until evenly combined.
03 - In a separate large bowl, blend nut-milk pulp, sugar, melted coconut oil or butter, eggs, and vanilla until mixture is smooth and well integrated.
04 - Gradually fold dry mixture into wet ingredients, mixing only until just combined; avoid overmixing.
05 - Gently stir in chocolate chips and nuts, if using.
06 - Pour batter into prepared pan, smoothing the surface. Bake for 28 to 32 minutes, or until a toothpick inserted in the center yields a few moist crumbs.
07 - Allow brownies to cool fully in the pan. Once cooled, slice into squares for serving.