In a bowl, whisk together the cake flour, salt, and baking soda

In a stand mixer, combine the melted, cooled butter with both sugars (granulated and brown). Mix on low until combined, then increase to medium-high and beat until just lightened in color, about 1 minute

Add the egg yolks, whole milk, and vanilla extract. Mix on low until well combined. The batter will be quite wet, which helps the cookies spread and become thin and crispy

Add the flour mixture to the wet ingredients and mix on low until just combined. Finish incorporating any remaining flour by hand to avoid overmixing, which ensures a crisp, light texture

Stir in the mini chocolate chips by hand. Mini chips are preferred as they help the cookies stay thin and provide more chocolate in each bite

Using a tablespoon measure (sprayed with nonstick spray for easier release), portion out heaping tablespoons of dough onto parchment-lined baking sheets, spacing them well apart as the cookies will spread. Place only 8 cookies per tray

With damp fingers, press each dough mound down to about ?½-inch thick before baking. This helps the cookies spread evenly and become thin

Bake one sheet at a time at 350°F, rotating halfway through, for about 16-18 minutes, until the cookies are deep golden brown all over-not just at the edges. This ensures a crispy texture throughout

Let the cookies cool completely on the baking sheet for about 20 minutes. They will firm up and become crisp as they cool

Cake flour and melted butter are key to the thin, crisp texture.

Using only egg yolks (no whites) and a bit of milk makes the dough wetter, promoting spread and crispiness.

Mini chocolate chips distribute more evenly and help keep the cookies flat.

Pressing the dough before baking and allowing the cookies to cool on the sheet are essential steps for maximum crispness