Step 1

Preheat the oven to 350°F and line a 13x18-inch rimmed baking sheet with parchment paper. Set aside.

Step 2

In a large bowl, beat the butter and sugars with an electric mixer on medium until light and fluffy, about 2 minutes. Scrape the bottom and sides of the bowl, and add the eggs and yolks, one at a time, beating well after each addition. Mix in the vanilla extract last.

Step 3

Add the flour, cornstarch, baking soda, and salt and stir gently with a spatula until almost combined. Add 2 cups of chocolate chips and mix until no flour streaks are visible.

Step 4

Press the cookie dough evenly into the prepared baking sheet. Sprinkle additional chocolate chips and sea salt on top, if desired. Then bake for 20-25 minutes, until the top is lightly golden brown.

Step 5

Remove the sheet tray from the oven and let the cookies cool for at least 20 minutes before lifting them out of the tray and placing them onto a wire rack to cool fully.

Step 6

Slice into bars, serve, and enjoy warm or at room temperature!