Preheat the oven to 350°F (180°C) and line a baking sheet with parchment paper.
In a medium bowl, whisk together the flour, baking powder, baking soda, and cornstarch. Set aside.
In a large mixing bowl, cream together the dark brown sugar, granulated sugar, and softened butter until light and fluffy, about 3-4 minutes.
Add the cold eggs, one at a time, beating well after each addition. Stir in the vanilla bean paste and continue to beat until the mixture becomes pale and smooth.
Gradually add the dry ingredients to the wet mixture, mixing just until combined. Be careful not to overmix to ensure a tender cookie.
Gently fold in both the semi-sweet and dark chocolate chips, ensuring an even distribution throughout the dough.
Using a cookie scoop or spoon, drop dough balls of 3-4 tablespoons each onto the prepared baking sheet. For a rustic texture, leave the dough balls slightly rough and stacked. Place only 4 cookies on each baking sheet, ensuring 4 inches of space between each.
Top the dough with additional chocolate chips for an extra indulgent look.
Bake for 13-16 minutes, or until the edges of the cookies are lightly golden brown. For the best results, bake on the middle rack of your oven.
Once baked, remove the cookies from the oven and allow them to cool on the baking sheet for 5 minutes. Then, transfer them to a wire rack to cool completely.
