Pre-heat oven at 350 degrees Fahrenheit (180 degrees Celsius) and line a baking tray with parchment paper.
In a bowl, sift together flour, matcha powder, salt and baking powder. Stir with a whisk to combine, and set aside.
Place sofenned butter in a seperate bowl and use an electric mixer to whip the butter until fluffy.
Add the sugar and continue whipping with your electric mixer until the mixture becomes light and creamy.
Add vanilla extract, egg and egg yolk and mix again until combined.
Add dry ingredients to butter mixture and mix together using the electric mixer.
Add the chocolate chips to the cookie dough and stir through.
Roll the cookie dough into golf ball sized balls and place them onto the prepared tray. The cookies will spread slightly, so leave an inch or so space between each cookie.
Bake for 10-12 minutes. Baking time will depend on your oven.