Preheat oven to 325F. Line a 8x8-inch baking pan with parchment paper.
In a small bowl, combine flour, baking soda, salt, and matcha powder. Set aside.
¾ cup flour, ¼ teaspoon baking soda, ¼ teaspoon salt, 2 tablespoons matcha powder
In a small saucepan, heat the butter and add the white sugar, brown sugar, and water. Bring just to a boil then remove from heat. Immediately add the chopped white chocolate and vanilla. Stir until the white chocolate has melted and the mixture is smooth.
⅓ cup butter, ½ cup granulated sugar, ¼ cup brown sugar, 2 tablespoons water, 4 ounces white chocolate baking bar, 1 teaspoon vanilla
Transfer the white chocolate mixture to a large bowl. Add the eggs, one at a time, beating well after each addition.
2 eggs
Gradually blend in the flour mixture by adding about a third at a time, mixing in well, then adding another third until all of the flour mixture has been completely incorporated.
Transfer batter into the prepared baking pan.
Bake the brownies in the preheated oven for 30-35 minutes. Allow to cool completely in the pan before cutting.