Instructions

1. Whisk the flour, baking powder, baking soda, and salt together in a small bowl; set aside. Cream the butter, tahini, and brown and granulated sugars together in a stand mixer fitted with the paddle attachment on medium speed until light and fluffy, about 3 minutes. Add the egg, return the mixer to medium speed, and mix until completely incorporated. Stop the mixer and scrape down the sides and the paddle.
2. Return the mixer to low speed and slowly add the flour. Stop the mixer when almost all the flour is incorporated, then use a rubber spatula to incorporate the last of it by hand. Cover with plastic wrap and refrigerate until starting to firm up, 1 to 1 1/2 hours.
3. Arrange a rack in the middle of the oven and heat to 350°F. Line 3 baking sheets with parchment paper. (If you don't have 3, you can reuse baking sheets and parchment, just let the baking sheet cool completely between uses). Place the coarse sugar in a shallow, wide bowl or pie plate.
4. Scoop the dough by level tablespoons and roll into balls. Roll each ball in the sugar to lightly coat. Place the dough balls on the baking sheets 2 inches apart, 12 per baking sheet. Using the back of a fork, flatten each cookie to about 1/2-inch thick with a criss-cross pattern.
5. Bake one sheet at a time until the cookies are a light golden-brown around the edges and on the bottoms, 12 to 14 minutes. Let cool for 2 minutes on the baking sheet, then transfer to a wire rack to cool completely. Store in an airtight container at room temperature for up to 5 days.