Preheat your oven to 350 degrees Fahrenheit. In a medium-sized bowl, whisk the flour, matcha powder, baking soda, and salt.
In a large bowl, cream the butter and sugars with electric beaters for 2 minutes. Beat in the egg and vanilla.
Add the flour mixture and beat on low speed just until combined. Fold in the white chocolate chips.
Use a medium-sized cookie scoop (about 2 tablespoons) to portion the dough into 18 cookies. Press the tops of the cookies down slightly then bake them in the oven for 10-12 minutes, until the bottoms are very lightly browned.
Remove the cookies from the oven and let them cool for 5 minutes on the baking sheet before transferring them to a cooling rack to cool completely.
