In a big bowl, mix the matcha green tea powder and all-purpose flour.
Matcha powder and flour should be sifted.
Beat the unsalted butter until it is smooth and creamy using a hand mixer or a paddle attachment on a stand mixer. It's crucial to soften the butter in advance.
Blend with a pinch of salt.
Beat well after adding the powdered sugar until it is soft and light. Stop the mixer occasionally while blending to scrape down the bowl.
When mixed, add the egg yolks and stir well.
Add the flour mixture gradually while blending the matcha mixture until barely mixed.
The dough should be divided in half if you're preparing 24 cookies. Form into cylinders that are 7 inches (18 cm) long and 112 inches (4 cm) in diameter.
The logs should be covered in plastic wrap and chilled for at least two hours to reach firmness.
Set the oven's temperature to 350°F (175°C). Reduce the cooking temperature by 25oF (15oC) for a convection oven. Use silicone baking liners or parchment paper to line a baking pan. Take the dough out of the fridge, then remove the plastic wrap.
After being taken out of the oven, the cookies should cool for five minutes on the baking sheet before being carefully moved to a wire cooling rack to finish cooling.