Preheat oven to 350°F and line baking sheets with parchment paper.
In a large bowl, beat butter, brown sugar, and granulated sugar until light and fluffy, about 2–3 minutes.
Add eggs and vanilla extract and mix until smooth.
In a separate bowl, whisk together flour, cornstarch, baking soda, baking powder, and salt.
Add dry ingredients to wet ingredients and mix just until combined.
Fold in mini chocolate chips.
Scoop large dough balls, about 1/4 cup each, and place on baking sheet.
Chill dough for 30–45 minutes.
Slightly flatten tops.
Bake for 11–13 minutes, until edges are set and centers remain soft.
Let cookies cool completely before frosting.