Mix the dry ingredients. In a medium bowl, whisk together the flour, cornstarch, baking soda and salt until combined. Set aside.

Mix the wet ingredients. Using a separate mixing bowl, either with a stand mixer or a hand mixer, cream together the softened butter and sugars on medium-high speed until the mixture is light and fluffy and a pale yellow color, about 2 minutes. Add egg and vanilla extract and mix on medium-speed until combined, about 1 minute.

Combine. Add in the dry ingredient mixture and beat on medium-low speed until just combined.

Chill the dough. Transfer the dough to an airtight container and refrigerate it for 2 hours, or until it is chilled through. (Or, for a speedier solution, you can go ahead and shape the dough into 1-inch balls, place them on a baking sheet that is covered with either parchment paper or a silicone baking mat. Then chill in the refrigerator for 20 minutes.)

Prep the oven and baking sheet. Heat the oven to 350°F. Line a large baking sheet with parchment paper.

Form the dough balls. Scoop and roll the chilled dough into 1-inch balls and place on the prepared baking sheet.

Bake. Bake for 10-12 minutes or until the edges are slightly crispy and the tops of the cookies are very lightly golden. The centers may look slightly undercooked, which is okay. Transfer the baking sheet to a wire cooking rack for 5 minutes.

Serve. Serve the cookies while they’re warm and gooey and enjoy!