Preparation

• Step 1
  If using whole or ground tea leaves or ground coffee, process or blend ¼ cup (50 g) granulated sugar and 2 Tbsp. whole or ground tea leaves or ground coffee (see chef’s note) in a food processor until tea or coffee is ground to a coarse powder, 1–2 minutes, then transfer to the bowl of a stand mixer fitted with the paddle attachment.
  Step 2
  If using powdered tea or coffee, mix ¼ cup (50 g) granulated sugar and 2 Tbsp. powdered tea (such as matcha or hojicha) or instant coffee or espresso powder in the bowl of a stand mixer to combine, then attach bowl to mixer fitted with paddle attachment.
  Step 3
  Add 1 large egg yolk, 1 cup (2 sticks) unsalted butter, room temperature, ¾ cup (83 g) powdered sugar, and 1 Tbsp. vanilla bean paste or vanilla extract and beat on medium-high speed, scraping down sides of bowl as needed, until light and fluffy, about 2 minutes. Turn off mixer.
  Step 4
  If using whole or ground tea leaves or ground coffee, add 2⅓ cups (292 g) all-purpose flour. If using powdered tea or coffee, add 2 cups plus 3 Tbsp. (276 g) all-purpose flour. Add 2 tsp. Diamond Crystal or 1¼ tsp. Morton kosher salt and mix on low speed just until a soft dough forms with no dry streaks left, about 1 minute.
  Step 5
  Transfer dough to a surface and roll into a 9½x1¾" log. Sprinkle ½ cup (60 g) raw sugar onto a rimmed baking sheet or large rimmed plate and roll log in sugar, gently pressing it into sides to adhere, until evenly coated. Tightly wrap in plastic and chill in freezer at least 30 minutes.
  Step 6
  Place racks in upper and lower thirds of oven and preheat to 350°. Cut log into ⅓"-thick rounds. (If the dough is too cold to slice and starts to crumble, let sit at room temperature 10 minutes, then try again.) Divide shortbread between 2 parchment-lined baking sheets, spacing at least 2" apart. Chill in freezer 15 minutes.
  Step 7
  Bake shortbread, rotating pans top to bottom and front to back halfway through, until matte looking, fragrant, and golden brown around the edges, 20–24 minutes. Let cool on baking sheets.
  Do ahead: Dough can be made 1 week ahead. Keep frozen.