Gather all the ingredients so you have everything at hand.
Mixing
Sift and combine the 240 g all-purpose flour and the 15 g matcha green tea powder in a large mixing bowl.
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. Gradually add the flour and matcha mixture until just combined. Add 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.
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.
Serving
Transfer the cookies to a cooling rack and let them cool completely before serving.