01 - Preheat the oven to 350°F. Line a 9x9 inch baking pan with parchment paper, leaving an overhang on the sides for easy removal.
02 - In a medium bowl, whisk together flour, cocoa powder, baking powder, and salt until evenly incorporated.
03 - In a large bowl, whisk the melted butter with granulated sugar until combined and glossy. Add eggs one at a time, whisking well after each addition, then stir in vanilla extract.
04 - Fold the dry ingredients into the wet mixture gently with a spatula just until combined. Avoid overmixing to maintain a tender texture.
05 - Gently fold in the chocolate chips or chopped dark chocolate until evenly distributed.
06 - Pour the batter into the prepared pan and smooth the surface with a spatula.
07 - Bake for 28 to 32 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs but no wet batter.
08 - Allow the brownies to cool completely in the pan before lifting out using the parchment overhang and cutting into 12 squares.