Preheat the oven to 350 degrees F. Line a large baking sheet with parchment paper and set aside.

In a medium bowl, whisk together 2 3/4cups all-purpose flour (spooned and leveled), 2 teaspoons cornstarch, 1 teaspoon baking soda, 3/4 teaspoon salt, and 1/2 teaspoon baking powder. Set aside.

In the bowl of a stand mixer fitted with the paddle attachment, beat 1 cup unsalted butter (at cool room temperature) on medium speed for 1 minute.

Add 1 3/4 cup granulated sugar and beat on medium speed until the mixture is light and fluffy, about 2 minutes. Stop the mixer and scrape down the sides of the bowl with a spatula as needed.

Add 1 large egg, 1 large egg yolk, and 1 tablespoon pure vanilla extract. Mix on medium-low until well combined.

With the mixer off, add the dry ingredients to the wet mixture. Mix on low speed just until the dough comes together and no large streaks of flour remain—do not overmix.

Fold in 1 cup mini chocolate chips with a spatula until evenly distributed.

Pour 1/3 cup granulated sugar (for rolling) into a small bowl.

Using about 2 tablespoons of dough per cookie, form dough into balls. Roll each ball in the 1/3 cup sugar until well coated. Place the coated dough balls on the prepared baking sheet about 2 inches apart.

Gently press extra mini chocolate chips on top of each dough ball for garnish, if desired.

Bake for 10 to 12 minutes, checking at 10 minutes. Bake until the cookies start to crack and are slightly set at the edges but still soft in the centers. Do not overbake.

Remove the baking sheet from the oven and, if using, sprinkle flaky sea salt on the warm cookies. Let the cookies cool on the baking sheet for 5 minutes, then transfer them to a cooling rack to cool completely.