01 - Preheat the oven to 350°F. Line an 8-inch square baking pan with parchment paper, leaving an overhang for easy removal.
02 - In a medium bowl, whisk together flour, cocoa powder, baking powder, and salt until well combined. Set aside.
03 - In a large mixing bowl, combine melted butter, sugar, and black sesame paste. Whisk until smooth and glossy.
04 - Add eggs one at a time, whisking thoroughly after each addition. Stir in vanilla extract until fully incorporated.
05 - Gently fold the dry ingredients into the wet mixture using a spatula. Mix until just combined, being careful not to overmix.
06 - Fold in the chopped dark chocolate until evenly distributed throughout the batter.
07 - Transfer the batter to the prepared pan, smoothing the top with a spatula. Sprinkle black sesame seeds evenly over the surface if desired.
08 - Bake for 28–32 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs attached.
09 - Allow the brownies to cool completely in the pan. Using the parchment overhang, lift out the slab and slice into 12 squares.