In a large mixing bowl, cream together softened butter, brown sugar, and granulated sugar until fluffy (about 3–4 minutes).
Add eggs one at a time, mixing after each. Stir in vanilla extract.
In a separate bowl, whisk together flour, cornstarch, baking soda, baking powder, and salt.
Slowly mix the dry ingredients into the wet mixture until just combined.
Fold in the chocolate chips, reserving a few for topping if desired.
Chill the dough for at least 30 minutes (optional but recommended).
Preheat oven to 375°F (190°C). Line a baking sheet with parchment paper.
Scoop dough into large 1/3 to 1/2 cup balls and place spaced apart on the baking sheet.
Bake for 12–14 minutes, until edges are golden but centers still look soft.
Let cookies cool on the sheet for 5 minutes before transferring to a wire rack. Press extra chips on top if desired.