Preheat oven to 170C (340F). Place the parchment paper in a 16cm×16cm (6.3inch×6.3inch) pan. Shift flour, green tea, and baking powder together.
Microwave the butter and shredded white chocolate until it melts. Add sugar and mix.
Add the eggs to mixture a third at a time.
Combine all the dry ingredients with a spatula. Mix white chocolate chip and cashew nuts.
Pour the mixture into the pan.
Bake for 15 to 20 minutes. If you it starts to brown on the top, cover with aluminum foil.
Try this with vanilla ice cream when it's hot! Woooow!