01 - Preheat oven to 350°F. Line an 8x8-inch baking pan with parchment paper.
02 - In a medium bowl, whisk flour, cocoa powder, baking powder, and salt until thoroughly blended.
03 - In a large bowl, blend nut-milk pulp, sugar, melted coconut oil or butter, eggs, and vanilla extract until smooth.
04 - Gradually fold dry ingredients into wet mixture until just incorporated; avoid overmixing.
05 - Gently stir in chocolate chips and chopped nuts, if using.
06 - Spread batter evenly into prepared pan, smoothing the top.
07 - Bake for 28 to 32 minutes, or until a toothpick inserted into the center yields a few moist crumbs.
08 - Allow brownies to cool fully in the pan before slicing into squares.