1. Preheat & Prep
Preheat your oven to 350 °F (≈ 175 °C). Line two baking sheets with parchment paper.
In a bowl, whisk together the flour, matcha powder and salt. Set aside.

2. Make the Dough
In a mixing bowl, beat the softened butter until smooth and creamy.
Add the powdered sugar and continue to beat until light and well-combined.
Add the egg yolks, one at a time, and mix until smooth.
Gradually add the flour/matcha mixture and mix until just combined — avoid over-mixing.
Fold in the white chocolate chips, if using.

3. Shape, Chill & Bake
Shape the dough into two logs (each ~1½ inches in diameter) or roll into cookie balls (depending on preferred shape/size).
If using logs, wrap in plastic and chill for at least 2 hours until firm — this helps with slicing and proper shape.
Slice logs into ⅓-inch (≈ 7 mm) rounds and place on prepared baking sheets, leaving ~1 inch (2.5 cm) between cookies.
Bake for 8–12 minutes, or until the edges are lightly set and the cookies hold their shape.
Let cookies rest on the baking sheet for ~2 minutes, then transfer to a wire rack to cool completely.