1 1/4 cups all-purpose flour, preferably unbleached
1/2 cup corn starch
1/4 teaspoon fine sea salt
1/2 cup sugar
8 ounces best-quality salted butter, cubed and chilled
1 teaspoon vanilla extract
Preheat the oven to 300ºF (150ºC).
Lightly butter a 9-inch (23 cm) tart ring or springform pan with a removable bottom.
Whisk together the flour, corn starch, salt, and sugar in the bowl of a stand mixer.
Add the butter and mix on low speed until the mixture starts coming together in clumps.
Add the vanilla and continue to mix until the dough forms solid clumps.
Use the heel of you hand to press the dough evenly into the tart pan. (If using a springform pan, you can use the bottom of a glass to tamp it evenly into the pan. A sprinkle of flour or confectioners sugar may be needed if it’s sticking too much.) You want the top to be a smooth as possible.
With a sharp knife, score the shortbread into twelve even wedges and prick each wedge three time with the tines of a fork.
(Note: When I baked these at home, using French butter, both the score marks and the tines disappeared. So be aware that that’s something that might happen. If so, just continue on and cut the shortbread as directed in the next step.)
Bake the shortbread for 45 to 55 minutes, or until the top is light golden brown. Remove from oven and immediately use a sharp knife to cut completely through the dough, where you previously marked it, into wedges. Let the shortbread cool completely in the pan. Once cool remove the outer ring of the tart (or springform) pan, and separate the wedges.