Cream the softened butter, dark brown sugar, and white sugar together using a stand mixer or hand mixer on medium speed until light and fluffy (about 2-3 minutes).
Add the eggs one at a time, mixing well after each addition. Then, pour in the vanilla extract and beat until fully combined.
In another bowl, whisk together the all-purpose flour, cornstarch, baking soda, and salt.
Gradually add the dry ingredient mixture to the wet ingredients. Mix on low speed until just combined, being careful not to overmix.
Fold in the mini semi-sweet chocolate chips using a spatula until evenly distributed.
Cover the bowl with plastic wrap and chill the dough in the refrigerator for at least 30 minutes.
Preheat your oven to 350°F (175°C) and line your baking sheets with parchment paper.
Scoop the dough onto the prepared baking sheets, leaving space for spreading. Bake for 10-12 minutes until the edges are lightly golden but the centers are still soft.
Allow the cookies to cool on the baking sheets for about 5 minutes before transferring them to a wire rack to cool completely.
