Line two baking sheets with parchment paper. (You can also bake in batches if you only have one cookie sheet).

In a medium-sized bowl, whisk together the flour, cornstarch, and salt.

In a stand mixer fitted with the paddle attachment, cream the butter and sugar on medium-high speed for 6-7 minutes, scraping down the sides of the bowl once or twice, until light and fluffy. Add the vanilla and mix for an additional 30 seconds.

Turn the speed down to low and add the flour mixture in 2-3 batches until just combined.

Use a tablespoon-sized scoop to portion out the cookies, rolling briefly in your palm to smooth the dough. (Note: if the dough is too soft to work with, chill in the refrigerator for 15 minutes). Place on the prepared baking sheets, spacing 1-2 inches apart.

Use a fork to gently flatten and create lined indentations in each cookie (you can dip the fork in confectioners’ sugar if it sticks to the cookie dough). If using, sprinkle with jimmies or sanding sugar.

Chill the baking sheets for 30 minutes. Meanwhile, place an oven rack on the upper and lower shelves and preheat the oven to 325 degrees F.

Bake for 11-13 minutes, then cool completely before serving.