In a medium bowl, whisk together 2 cups of all-purpose flour, 1 teaspoon of baking soda, 1/2 teaspoon of salt, 1/4 cup of cornstarch, and 2 tablespoons of premium matcha powder until evenly combined. Set aside.

In a stand mixer, beat together 3/4 cup of room temperature unsalted butter, 1/2 cup of light brown sugar, and 1/2 cup of white sugar on medium speed until light and fluffy, approximately 2-3 minutes.

Add 1 egg, 1 egg yolk, and 1 teaspoon of vanilla extract to the mixture. Continue mixing on medium speed until fully incorporated, about 1 minute.

Gradually add the dry ingredients to the wet mixture in the stand mixer, mixing on low speed until just combined to form a soft dough, approximately 1-2 minutes.

Cover the dough with plastic wrap and refrigerate for 30 minutes.

Preheat your oven to 180°C (350°F). Line a baking sheet with parchment paper. Scoop tablespoon-sized portions of dough onto the prepared baking sheets, leaving space between. Bake for about 10 minutes until golden at the edges.

Allow cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.