01 - Preheat oven to 350°F (175°C). Line an 8x8 inch (20x20 cm) baking pan with parchment paper, leaving an overhang for easy removal.
02 - In a medium mixing bowl, whisk together the all-purpose flour, matcha powder, and fine sea salt until evenly blended.
03 - In a large mixing bowl, whisk melted butter and granulated sugar until glossy and thoroughly combined.
04 - Add eggs one at a time, whisking thoroughly after each addition. Stir in vanilla extract until incorporated.
05 - Gradually fold the dry mixture into the wet ingredients using a spatula, mixing just until combined for a tender texture. Do not overmix.
06 - Gently fold in the chopped white chocolate and nuts, if using, making sure they distribute evenly throughout the batter.
07 - Pour batter into the prepared pan, smoothing the top. Bake for 22 to 25 minutes, or until the center is just set and a toothpick inserted comes out with a few moist crumbs.
08 - Allow brownies to cool completely in the pan before lifting out using parchment overhang. Slice evenly into 16 squares.