In a small bowl, whisk together all purpose flour, baking soda, salt, cornstarch, and matcha powder
In a mixing bowl, add the room temperature butter, brown sugar, and white sugar
Beat for about a minute or two until light and fluffy using a hand mixer or stand mixer fitted with a paddle attachment
Add the egg, egg yolk, and vanilla extract. Beat again until smooth. Scrape the sides of the bowl as necessary
Add the dry to the wet and combine until a dough forms
Mix in the white chocolate chips and let the dough rest for 20 minutes
Preheat oven to 350°F.
Line a sheet pan with parchment paper
Scoop out portions of the dough about the size of 1/4 to 1/3 measuring cup. Make sure to space them apart, 6 cookies per sheet.
Pop in the oven to bake for about 11 to 12 minutes until the edges are golden and the center is still a bit soft. The cookies will continue baking out of the oven on the hot pan.
Leave them on the pan for about 10 minutes or until firm before transferring them to a cooling rack to finish cooling. Enjoy!