Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a medium bowl, whisk together the flour, matcha powder, baking powder, baking soda, and salt. Set this aside while you work on the wet ingredients.
In a large mixing bowl, beat the softened butter, granulated sugar, and brown sugar until light and creamy. This usually takes about 2–3 minutes with a hand mixer, or a bit longer by hand with a sturdy spatula.
Add in the egg and pour in the vanilla extract. Beat again until smooth and fully incorporated.
Gradually add the dry ingredients to the wet ingredients, mixing until a dough forms.
Gently fold in the chopped Oreo cookies. You want them distributed evenly throughout the dough, but don’t overmix or they’ll turn the dough grayish.
Scoop out the dough into 1.5 tablespoon-sized balls and place them a couple inches apart. Press a couple extra chopped Oreos into the tops of the cookies before you baking them for a pretty effect.
Bake for 9–12 minutes, or until the edges are just set and the centers still look slightly soft. Let them cool on the baking sheet for 5 minutes before transferring to a wire rack.