Preheat your oven to 350°F (175°C). Line your 8x8-inch baking pan with parchment paper, leaving an overhang on the sides for easy removal later.
In a large bowl, combine the melted unsalted butter and brown sugar. Whisk until smooth and glossy. Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.
In a separate bowl, sift together the all-purpose flour, matcha powder, baking soda, and salt. This ensures even distribution of the matcha and prevents clumps.
Gradually add the dry ingredients to the wet ingredients, folding gently with a spatula until just combined. Avoid overmixing to keep the blondies tender.
Fold in the white chocolate chips and roughly chopped pistachios, reserving a small handful of each to sprinkle on top before baking.
Pour the batter into the prepared pan, smoothing the top with your spatula. Sprinkle the reserved white chocolate chips and pistachios evenly over the surface. Bake for 25-30 minutes or until a toothpick inserted in the center comes out with just a few moist crumbs.
Allow the blondies to cool completely in the pan on a wire rack. Use the parchment paper overhang to lift them out. Cut into squares and enjoy!