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, baking powder, and salt until well combined.
03 - In a large bowl, whisk melted butter, brown sugar, and granulated sugar until combined and glossy.
04 - Add eggs one at a time, whisking well after each addition. Stir in vanilla extract and black sesame paste until fully incorporated.
05 - Fold in the dry ingredients using a spatula until just combined. Do not overmix to maintain tender texture.
06 - Gently fold in half of the toasted black sesame seeds and optional white chocolate chips until evenly distributed.
07 - Spread the batter evenly in the prepared pan. Sprinkle the remaining black sesame seeds on top for visual appeal.
08 - Bake for 22–26 minutes, until the center is just set and a toothpick inserted comes out with a few moist crumbs.
09 - Cool completely in the pan before lifting out using parchment overhang and cutting into squares.