Cream wet ingredients together - Add softened butter, sugar vanilla, and salt to a stand mixer bowl fitted with the paddle attachment. Beat on medium speed until the mixture is thoroughly incorporated and creamy.
8 ounce unsalted butter, ⅔ cup granulated sugar, ¼ teaspoon kosher salt, 1 tablespoon pure vanilla extract
Add dry ingredients - Sift flour and cornstarch into another mixing bowl, and whisk to distribute evenly. Add the mixture into the stand mixer bowl with the creamed butter. Stir to combine, then increase the mixer speed and beat until no trace of flour remains and the dough is formed.
2 ¼ cup all-purpose flour, 2 tablespoon cornstarch
Form the logs - Place 2 long pieces of plastic wrap flat on the countertop. Divide cookie dough into 2 equal portions. Roll each portion on top of the plastic wrap into a log about 6” in length. Wrap it up and refrigerate for at least 1 hour before baking.
Slice the cookies - Use a sharp knife to slice each cookie dough log into 12 cookies about ½” thick. Rewrap in the same plastic and place them in the freezer for about 15 minutes, while the oven preheats.
Preheat the oven - Set the oven rack in the middle of the oven and preheat to 350°F.
Bake - Mix 1-2 tablespoon of granulated sugar with a few pinches of kosher salt in a small bowl. Place 12 cookies on a large lined baking sheet, about 2 inches apart. Sprinkle the sugar mixture on top and bake 1 batch at a time for about 20 minutes, until the edges on the cookies are golden brown. You don't have to add salt to the sugar topping but I highly recommend it for that pop of saltiness.
Extra sugar for sprinkling, Extra salt for sprinkling
Cool - Remove the baking sheet from the oven, but allow the cookies to sit on the baking sheet to finish baking from the residual heat for 5-10 minutes before removing them to a wire rack to cool completely.
Decorate the cookies (optional)
Melt chocolate - Melt chocolate in a heatproof glass bowl over a small pot of simmering water over medium low heat, double boiler style. Or melt it in the microwave in short burst.
¾ cup dark chocolate melting wafers
Coat cookies in chocolate - Cover the cookies half way with melted chocolate by dipping them into the bowl or spooning the chocolate over the cookies. Let the excess chocolate run off back into the bowl and place the cookies back on the parchment lined baking sheet to harden.
Add sprinkles - Add them as soon as you place the cookies on the baking sheet before the chocolate hardens.
Sprinkles
Notes
Upgrade to high quality butter for more amazing taste.
Storing baked cookies: store your shortbread cookies in an airtight container at room temp for up to a week.
Storing cookie dough: Unbaked shortbread dough can be kept refrigerated for 3-4 days, or freeze for 3-6 months. It is best to slice the log first before freezing.
Baking frozen dough: no need to thaw frozen cookie dough, you can bake directly from the freezer.
Nutrition facts are for non-coated cookies.
Alternate way to shape shortbread: instead of rolling the dough into a log, you can roll it out into a sheet and cut into shape with cookie cutters. Adjust baking time as necessary. See the post for more details and example.