This satisfying shortbread is as easy as it gets. It’s simultaneously crisp, crumbly and tender because we’ve added a little cornstarch to the flour. And granulated sugar gives the cookies their gorgeous golden color.
Yields 36 bars.
Cook’s NoteWhen measuring flour, we spoon it into a dry measuring cup and level off the excess. (Scooping directly from the bag compacts the flour, resulting in dry baked goods.)
Position an oven rack in the center of the oven and preheat to 325ºF. Butter a 9-by-12-1/2-inch jelly roll pan and line it with parchment, then butter the paper.
Whisk together the flour, cornstarch and salt in a bowl. Beat the butter and sugar with an electric mixer on medium speed until light and fluffy, 5 to 7 minutes. Slowly add the flour mixture and beat on low until the dough is just combined; do not overwork.
Transfer the dough to the prepared pan, spreading it out as evenly as possible with a spatula. Cover with plastic wrap, then use your hands to press and flatten the dough into a smooth even layer. Remove the plastic and cut the dough with a sharp knife into approximately 1-by-3-inch bars. Use a fork to prick a decorative pattern into the tops.
Bake, rotating the pan from front to back halfway through, until golden, 60 to 70 minutes. Let stand for 5 minutes in the pan, then re-cut the bars along the previous cuts. Carefully lift the bars off the parchment with a small spatula and transfer them to a wire rack to cool completely. Store the cookies in an airtight container for up to 5 days.