1-First Step: Preheat oven to 325F (165C) and line a baking sheet with parchment paper. Measure ingredients by weight if you can for consistent results. Soften butter to a spreadable but not oily consistency (about 65-70F).

2-Second Step: Beat butter and powdered sugar in a stand mixer or with a hand mixer on medium-high speed until light, pale yellow, fluffy, and creamy, about 5 minutes, scraping sides as needed.

3-Third Step: Stir in vanilla extract and salt until combined. Taste lightly if you used salted butter; reduce additional salt next time if the cookie comes out too salty.

4-Fourth Step: Whisk together flour and cornstarch in a separate bowl. Sifting or whisking aerates the flour and helps prevent lumps. Cornstarch helps the signature melt-in-your-mouth texture and limits gluten formation.

5-Fifth Step: Gradually add the flour mixture to the butter mixture on medium-low speed and mix just until combined. The key is to stop mixing as soon as the flour disappears; overmixing will deflate the whipped butter and yield a denser cookie.

6-Sixth Step: Scoop the dough into tablespoon-sized balls and roll briefly between palms to smooth. Place on the prepared baking sheet 1-2 inches apart. If dough is too soft to handle, chill 10-15 minutes.

7-Seventh Step: Gently flatten each cookie with a fork dipped in powdered sugar to prevent sticking, then sprinkle with decorating sugar if desired. Make only one-direction fork imprints; avoid crosshatching for best presentation.

8-Final Step: Bake for 12 minutes until cookies are lightly colored. Let cool completely on the baking sheet before removing. Overbaking will dry them out; these should be lightly colored, not brown.