in a stand mixer fitted with the paddle attachment, beat the cold, cubed butter with the brown sugar and granulated sugar on medium speed for 5 full minutes until well combined and creamy.
add the cold eggs one at a time, mixing just until incorporated. Add the vanilla extract and mix briefly again
gather your all-purpose flour, cake flour, cornstarch, baking soda, and sea salt. Add to the butter mixture and mix on low speed just until the dough comes together. Do not overmix.
add the chocolate chips and mix briefly on low until evenly distributed throughout the dough. its okay if there are a few streaks of flour still remaining
using a scale, divide the dough into 160g portions. You should get 8 large cookies. Roll each portion into a ball
now take your cookie dough ball, rip it in half, and press the two halves back together with the rough sides facing up. This helps create that signature craggy top like Levain Bakery cookies & it also gives the surface more texture so we can achieve a crispy top
place the dough balls on a tray or plate and refrigerate for at least 1 hour (overnight is even better for flavor and texture)
preheat your oven to 385°F (196°C). Line two baking sheets with parchment paper
arrange dough balls on the prepared baking sheets, spacing them at least 3 inches apart (no more than 3–4 per sheet). Bake for 15 minutes, or until the edges are golden brown and the tops are just set but still slightly underdone in the center
let the cookies sit on the baking sheet for 15–20 minutes. They’ll finish cooking and firm up as they cool
and you're done !!