Instructions

1. Place 2 sticks unsalted butter in the bowl of a stand mixer (or large bowl if using an electric hand mixer) and let sit at room temperature until softened. Add 1/2 cup granulated sugar and 1/2 teaspoon kosher salt. Beat with the paddle attachment on medium speed until light and airy, 60 to 90 seconds.
2. Add 1 large egg and 1 teaspoon vanilla extract, and beat until the egg is fully incorporated, about 1 minute. Add 2 1/4 cups all-purpose flour and beat on low speed until a crumbly dough forms. Transfer about 2/3 of the dough (about 2 cups) to another bowl.
3. Add 2 teaspoons matcha or 2 to 7 drops green gel food coloring to the remaining dough in the stand mixer. Beat on low speed until the dough is uniformly green, about 30 seconds. Add 2 tablespoons colored pearl sprinkles and beat on low speed just until combined.
4. Transfer the dough to a sheet of plastic wrap and form the dough into a 1-inch-thick disc. Wrap the dough up tightly in the plastic wrap. Freeze until firm but still pliable, about 45 minutes. Meanwhile, add 3 tablespoons of the white pearl sprinkles to the uncolored dough and mix with a flexible spatula until the sprinkles are well-distributed. Cover and let sit at cool room temperature.
5. Unwrap the green dough and place on a sheet of parchment paper. Roll out until 1/2-inch thick. Using a small (about 1 1/2-inch) Christmas tree cookie cutter, cut out as many trees as you can. Gather the scraps, roll out again, and cut out more trees (discard any scraps after this). Stack the trees on top of each other and gently press them together so they stick. Transfer the stack to a small baking sheet or plate and freeze until very firm, about 30 minutes.
6. Tear the plain dough into chunks. Press the chunks around the stack of green dough (sides, top, and bottom) so it is completely covered. Turn the stack on its side and roll it back and forth on the counter to form a log. Pour the remaining 1/2 cup white pearl sprinkles onto a plate or small baking dish, then roll the log in the sprinkles until the outer layer is fully covered (no need to do the ends).
7. Wrap the log in plastic wrap or parchment paper and freeze until firm, 20 minutes. Meanwhile, arrange a rack in the middle of the oven and heat the oven to 350ºF. Line 2 baking sheets with parchment paper or silicone baking mats.
8. Unwrap the dough and slice the dough crosswise into scant 1/2-inch-thick cookies. Arrange the cookies on the baking sheet, spacing them at least 1-inch apart, 10 per sheet. Sprinkle some more of the colorful pearl sprinkles onto the trees.
9. Bake one sheet at a time until the edges of the cookies are lightly golden-brown, 12 to 15 minutes. Let the cookies cool on the baking sheet for a few minutes. Transfer to a wire rack and let cool completely.