For any baking enthusiast, classic, buttery shortbread is a go-to recipe. After all, with a short list of almost-always-on-hand ingredients and a recipe that is quick to put together, these pat-into-the-pan, prick, and, bake shortbreads are in the oven before you know it. You can make this traditional style shortbread, or you can add a bit of flair: a teaspoon of vanilla extract, or, a tablespoon of lemon or orange zest; an equivalent amount of poppy seeds, or, 1/4 cup of finely ground hazelnuts or pecans. You could also substitute 2 tablespoons of the all-purpose flour with an equivalent of instant espresso powder and some cocoa powder.
1 cup unsalted butter, at room temperature, plus more for buttering pan
1⁄2 cup Caster Sugar
3 cups + 2 tablespoons plain flour
3⁄4 teaspoon fine sea salt
Generously butter the bottom and sides of the cake pan. Line the bottom of the pan with a circle of parchment paper, and butter the parchment. Set aside.
Place the butter in the bowl of your KitchenAid® Stand Mixer fitted with the flat beater. Attach the KitchenAid® Sifter + Scale Attachment to your mixer. With the ingredient valve closed, weigh the sugar in the ingredient hopper. Turn the mixer to medium-low speed, open the ingredient valve, and sift the sugar mixture into the mixing bowl. Cream the butter mixture, on medium speed, until the sugar is incorporated, about 1 minute. Scrape down the bowl once, beat until combined, 30 seconds longer.
Close the ingredient valve. Weigh the flour and salt in the ingredient hopper, taring the scale between ingredients. With the mixer on low speed, open the ingredient valve, and sift in the flour mixture. Beat on medium speed until the flour is incorporated and the dough turns yellow and starts to bind together, about 1 minute. Stop the mixer once to scrape down the sides of the bowl, and then mix about 30 seconds longer. Remove the mixer bowl, and use a rubber spatula to blend in any flour remaining on the sides of the bowl.
Turn the dough out onto a clean work surface, knead the dough a couple of turns, and then shape it into an 20-cm round patty that is 12-mm thick. Transfer to the prepared pan, patting it into place, and reshaping it, if needed, to form an even patty without cracks at the edges. Refrigerate for 30 minutes.
Position an oven rack in the center of the oven and preheat the oven to 160ºC.
Use the tip of a paring knife to score just the very top of the shortbread, forming 12 even wedges. It is easiest to score the shortbread into quarters and then evenly cut 3 wedges within each quarter section. If desired, prick the surface evenly with a fork, to form a consistent pattern.
Bake until the top of the shortbread is light golden and it begins to pull away from the sides of the pan, 40 to 45 minutes. Cool on a rack for 20 minutes. Run a table knife around the inside edge of the pan to loosen the shortbread. Invert the shortbread over the rack. Peel off the parchment paper, and then turn the shortbread right side up. Let cool completely. Cut into wedges to serve.
OPTIONAL ICING: Stir together 1/4 cup of icing sugar with a tablespoon of milk, lemon juice, brewed coffee, or maple syrup. Wait until the shortbreads are cooled and cut into wedges before drizzling icing over top.