If using unsalted butter then add ¼ teaspoon of salt. Be sure to use a good quality butter, apparently the year 2022, store brand butter quality is not what it used to be. Less fat could mean a dry not so tasty cookie.
Sift the flour, salt and cornstarch into a medium bowl.
In a large bowl cream the butter, sugar and vanilla then add the sifted flour mixture a little at a time, combine with a fork, when mixture begins to come together, move to a flat surface and knead until you have a smooth dough.
Wrap the dough in plastic and refrigerate for 30 minutes.
Remove dough from the fridge and roll on a lightly floured flat surface into a thickness of ¼ inch, dust the cookie stamp lightly with flour and firmly press on the dough, with a round cookie cutter (as close to the same size as the stamp) cut out the cookie. Place on 1-2 parchment paper lined baking sheets, continue until all are cut out. While the oven is pre-heating refrigerate the cookies for about 15-20 minutes.
Pre heat oven to 325F (163C).
Bake for approximately 15-20 minutes. Let cool completely before serving.
Video
Notes
If you don’t have a cookie stamp then you can use cookie cut outs or even roll the dough into a log instead of a ball and then slice and place on the prepared baking sheet.Shortbread is baked when it is a very light pale color. The baked cookies should be stored in an airtight container at room temperature for up to a week. I sometimes store mine in the fridge because I like cold cookies. They will last up to 10 days by storing them in the fridge.To freeze the shortbread cookies, place parchment paper in between the layers of the completely cooled cookies this prevents them from sticking together when they are in the containers for freezing, or you can also place the baked cooled cookies on a cookie sheet and freeze them, then move the frozen cookies to either airtight bags or containers. Baked Shortbread Cookies will last up to 6 months in the freezer.