01 - Preheat oven to 350°F (175°C). Line an 8x8-inch baking pan with parchment paper, allowing some overhang for easy removal.
02 - Whisk flour, cocoa powder, baking powder, and sea salt together in a medium mixing bowl until evenly blended.
03 - In a large bowl, stir nut-milk pulp, sugar, melted coconut oil or butter, eggs, and vanilla extract until the mixture is smooth and unified.
04 - Gradually fold the dry mixture into the wet ingredients, mixing just until combined. Avoid overworking the batter.
05 - Stir in the chocolate chips or chopped chocolate and, if desired, chopped nuts.
06 - Transfer the batter to the prepared pan and spread evenly, smoothing the surface as needed.
07 - Place pan in oven and bake for 28 to 32 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs clinging.
08 - Allow brownies to cool completely in the pan before slicing into squares for serving.