Preheat your oven to 375°F (190°C). Line a baking sheet with parchment paper or a silicone mat
Whisk together the flour, baking soda, and salt in a medium bowl. Set aside.
In a large bowl, use an electric mixer to cream together the butter and sugars until light and fluffy, about 2-3 minutes.
Beat in the eggs one at a time, followed by the vanilla extract.
Gradually mix in the dry ingredients (flour mixture) until just combined, being careful not to overmix.
Stir in the chocolate chips and cornstarch.
Scoop tablespoon-sized balls of dough onto the prepared baking sheet, leaving about 2 inches of space between each cookie.
Bake for 12-14 minutes, or until the edges are lightly golden brown.
Remove from the oven and let cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.