In the bowl of a stand mixer fitted with a paddle attachment, combine the butter, confectioners sugar, and salt. Beat on low speed just until combined. Increase the speed to medium and beat for about 3 minutes until light and fluffy.
Scrape down the sides and bottom of the bowl. Add the egg and almond extract. Beat on medium-low speed for about 1 minute. (The egg may not be fully incorporated, but the dough will smooth out once the flour is added.)
In a medium bowl, sift together the flour and matcha powder. With the mixer on low, gradually add the flour mixture, and mix just until combined. Scrape down the sides and bottom of the bowl. Add the pistachios and mix just until combined.
Turn the dough out onto a lightly floured surface and lightly flour your hands. Divide it into 2 equally-sized pieces and form each into a log shape, about 2 inches in diameter. Wrap tightly with plastic wrap and refrigerate for at least 2 hours, up to overnight.
About 20 minutes before you are ready to bake, place one oven rack in the top third of the oven and one in the bottom third. Preheat the oven to 350°F. Line two baking sheets with parchment paper.
Remove the cookie rolls from the refrigerator and unwrap the plastic wrap. Place the sparkling sugar on a plate. Roll the long sides of the pieces of dough in the sugar, pressing to adhere.
Slice the logs into ¼-inch thick cookies. Place the cookies about 1 inch apart on the prepared baking sheets.
Bake for 15 to 20 minutes, rotating the baking sheets from the upper to lower oven rack, and turning them 180° halfway through. Let the cookies cool for about 5 minutes on the sheet tray, then transfer to a wire rack to cool completely.
Notes
Weigh the flour. The most accurate way to measure flour is to weigh it with a kitchen scale. If you don’t have one, fluff the flour in its container, spoon it into the measuring cup, and use a knife to level off the top.
Use room temperature ingredients. To make the refrigerated ingredients (egg and butter) easier to combine, set them out about an hour before you start baking. If you forget to let the butter soften, follow my easy tutorial for how to soften butter.
I love using slivered pistachios! Shelled whole pistachios will also work, but you’ll need to chop them first. The pieces are less uniform, and you might have some gaps in the cookies, so buy slivered ones if you can!
Flour your hands. The dough is quite sticky, so lightly dust your hands with flour to make it easier to work with.
For perfectly circular cookies: After the logs of dough chill for about 1 hour, remove them from the fridge and roll them on the countertop into a neat, cylindrical shape. This helps to create a smooth, circular-shaped cookie once sliced, rather than having one flat side (from sitting in the fridge). Pop them back into the refrigerator to chill for the final hour after you do this.