Preheat oven to 350°F and line a baking sheet with parchment paper
In a medium mixing bowl, add your flour, matcha, salt, baking powder, and baking soda. Whisk to combine and set aside.
In a separate medium mixing bowl, add the butter, brown sugar, and white sugar. Use a hand mixer or stand mixer fitted with a paddle attachment to cream together on medium speed until light and fluffy. Add the vanilla extract and egg and mix to combine. Scrape down the sides of the bowl as needed.
Add the dry ingredients and mix on low until a cohesive dough forms. Be careful not to overmix. Fold in the ruby and white chocolate chunks, setting some aside to press into the top of the cookies later.
Shape 2 tbsp-sized balls of dough and place on the baking sheet about 2 inches apart. Take the chunks of chocolate you set aside and press a few chunks onto the top of each dough ball.
Place the cookies in the middle rack of the oven and bake for 10 - 12 minutes until the edges just start to brown. The center should still be puffy and soft.
Remove from the oven and immediately bang the tray a few times against the counter to create crinkled edges. Sprinkle with flaky sea salt and let cool for 5 minutes on the tray before moving to a wire cooling rack.