MAKES 16 WEDGES
Use the collar of a springform pan to form the shortbread into an even round. Mold the shortbread with the collar in the closed position, then open the collar, but leave it in place. This allows the shortbread to expand slightly but keeps it from spreading too far. The extracted round of dough in step 2 is baked alongside the rest of the shortbread. Wrapped well and stored at room temperature, the shortbread will keep for up to 7 days.
½ |
cup (1½ ounces) old-fashioned oats |
1½ |
cups (7½ ounces) unbleached all-purpose flour |
¼ |
cup cornstarch |
⅔ |
cup (2⅔ ounces) confectioners’ sugar |
½ |
teaspoon table salt |
14 |
tablespoons (1¾ sticks) unsalted butter, chilled, cut into ⅛-inch-thick slices |
1. Adjust an oven rack to the middle position and heat the oven to 450 degrees. Pulse the oats in a spice grinder or blender until reduced to a fine powder, about ten 5-second pulses (you should have ¼ to ⅓ cup oat flour). In a stand mixer fitted with the paddle attachment, mix the oat flour, all-purpose flour, cornstarch, sugar, and salt on low speed until combined, about 5 seconds. Add the butter to the dry ingredients and continue to mix on low speed until the dough just forms and pulls away from the sides of the bowl, 5 to 10 minutes.
2. Place an upside-down (the grooved edge should be at the top) collar of a 9- or 9½-inch springform pan on a parchment-lined rimmed baking sheet (do not use the springform pan bottom). Click here for press the dough into the collar in an even ½-inch-thick layer, smoothing the top of the dough with the back of a spoon. Place a 2-inch biscuit cutter in the center of the dough and cut out the center. Place the extracted round alongside the springform collar on the baking sheet and replace the cutter in the center of the dough. Open the springform collar, but leave it in place.
3. Bake the shortbread for 5 minutes, then reduce the oven temperature to 250 degrees. Continue to bake until the edges turn pale golden, 10 to 15 minutes longer. Remove the baking sheet from the oven; turn off the oven. Remove the springform pan collar; use a chef’s knife to score the surface of the shortbread into 16 even wedges, cutting halfway through the shortbread. Using a wooden skewer, poke 8 to 10 holes in each wedge. Return the shortbread to the oven and prop the door open with the handle of a wooden spoon, leaving a 1-inch gap at the top. Allow the shortbread to dry in the turned-off oven until pale golden in the center (the shortbread should be firm but giving to the touch), about 1 hour.
4. Transfer the baking sheet to a wire rack; cool the shortbread to room temperature, at least 2 hours. Cut the shortbread at the scored marks to separate and serve.