Cream butter and sugar. In the bowl of a stand mixer fitted with a paddle attachment, add the butter and sugar and beat on high speed for 2 minutes.

Add the egg and the egg yolk. Beat for another minute.

Right on top of the wet ingredients, add the dry ingredients. Add the all-purpose flour, baking powder, baking soda, salt, and matcha powder and mix to combine on medium speed

Fold in the white chocolate chips. Mix until just combined.

Chill cookie dough. Cover the mixer bowl with saran wrap and place in the refrigerator for at least 1 hour.

Prep your baking tools. Preheat the oven to 350 degrees F and line a cookie sheet with parchment paper.

Shape the dough. Using your hands or a cookie scoop, form the dough into balls using about 2 tablespoons of dough per cookie. The balls should be roughly 2.5 inches in diameter. Place the dough balls on a cookie sheet lined with parchment 2-3 inches apart. Gently flatten each one slightly by pressing down on each ball with the palm of your hand.

Bake for 10 – 12 minutes, until a crack forms. The cookies will still be quite soft when they are done and will harden as they cool.

Cool. Let the cookies cool for at least 5 minutes before transferring them to a wire rack to finish cooling completely.