Preheat oven to 350°F (175°C). Line two baking sheets with parchment paper or silicone mats. Measure and bring the butter to room temperature so it is soft but still cool to the touch.

Cream butter and sugars

In a large bowl or bowl of a stand mixer fitted with the paddle attachment, beat the softened unsalted butter for 30–45 seconds until smooth. Add granulated sugar and light brown sugar; beat on medium speed for 2–3 minutes until pale and fluffy, scraping down the bowl once.

Add eggs and vanilla

Add the eggs one at a time, beating just until incorporated after each addition, then add the vanilla extract and mix until combined. Do not overmix.

Combine dry ingredients

In a separate bowl, whisk together the all-purpose flour, baking soda, fine sea salt, and cornstarch until evenly combined.

Incorporate dry into wet

With the mixer on low, add the dry ingredients to the butter mixture in two additions, mixing just until no streaks of flour remain. Scrape the bowl and mix briefly by hand if necessary to ensure even incorporation.

Fold in chocolate chips

Using a spatula, fold the semisweet chocolate chips into the dough until evenly distributed.

Shape cookies

Scoop dough into 1.5-tablespoon to 2-tablespoon portions (roughly 1.25–1.5 ounces each) using a cookie scoop or tablespoon. For an even "Famous Amous" look, roll each portion into a smooth ball between your palms. If using, roll the balls lightly in the additional sugar to give a slightly sparkling exterior.

Chill (recommended)

Place shaped dough balls on a tray and chill in the refrigerator for 20–30 minutes if you prefer thicker, less spread cookies. This step is optional but improves texture and appearance.

Bake

Arrange dough balls on prepared baking sheets spaced 2 inches apart. If chilled, add 1–2 minutes to baking time. Bake in the preheated oven for 9–12 minutes, or until edges are set and centers are just beginning to color. Cookies should look slightly underbaked in the center for a soft chew.

Finish and cool

Remove baking sheets from oven. If using, immediately sprinkle a small pinch of coarse sea salt or flaked salt onto each hot cookie. Allow cookies to cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.

Finishing (optional)

Store baked cookies in an airtight container at room temperature for up to 4 days, or freeze baked cookies for up to 3 months. Unbaked dough balls can be frozen on a tray, then transferred to a sealed bag for up to 3 months; bake from frozen adding 1–2 minutes to baking time.