Gather the ingredients. Start by cutting into small pieces the 50 g white chocolate.
The Dry
Sift and combine the 240 g all-purpose flour and the 15 g matcha green tea powder in a large mixing bowl.
The Wet
In another large mixing bowl, beat the 170 g unsalted butter until smooth and creamy. If your butter is too hard, leave it out on the counter for 1 hour or microwave it in 5-second increments until it‘s softened.
Sift 130 g powdered sugar with 1/8 tsp. salt.
Add 2 egg yolk and mix well until combined.
The Dough
Gradually add the flour and matcha mixture until just combined.
Add the cut 50 g white chocolate and mix until just incorporated.
Divide the dough into 2 equal pieces.
Shape each piece into a cylinder about 1 1/2 inches (4 cm) in diameter and 7 inches (18 cm) long. Wrap the logs in plastic wrap and chill in the refrigerator until firm, at least 2 hours.
The Baking
Preheat the oven to 350ºF. Line a baking sheet with parchment paper. Remove the dough from the refrigerator, unwrap the plastic wrap and let it rest for 10 minutes. Use a sharp knife to slice the dough into rounds about 1/3 inch (7 mm) thick. Place the sliced dough on the baking sheet, leaving about 1 inch (2.5 cm) of space between the rounds.
Bake the cookies at 350ºF for about 15 minutes, or until the edges of the cookies start to get slightly golden brown on the sides.
The Serving
Transfer the cookies to a cooling rack and let them cool completely before serving. Enjoy your Japanese Matcha Cookies [日本の抹茶クッキー].