01 - Preheat oven to 350°F. Grease an 8x8-inch baking pan or line it with parchment paper.
02 - Whisk together almond flour, cocoa powder, baking powder, and salt in a medium bowl until evenly mixed.
03 - In a large bowl, whisk melted butter with granulated sugar, brown sugar, eggs, and vanilla extract until smooth and glossy.
04 - Gently fold the dry ingredient mixture into the wet mixture until just combined.
05 - Fold in dark chocolate chips and, if using, chopped nuts evenly throughout the batter.
06 - Pour batter into prepared pan and smooth the surface. Bake for 23 to 26 minutes, or until the center is set and a toothpick inserted comes out with moist crumbs.
07 - Allow brownies to cool completely in the pan before cutting into 16 squares.