Begin by warming your oven to 400 degrees Fahrenheit, or 385 degrees if you suspect your oven runs hot. Meanwhile, in a large bowl, beat the cold butter with both sugars until the mixture is fluffy and pale, about 4 minutes. Next, add eggs and vanilla extract and continue mixing for another minute until well combined. Combine the flour, cornstarch, baking soda, and salt together, then gently add these dry ingredients into the wet mixture, stirring just until everything comes together. Fold in your choice of chocolate chips carefully. If you have the time, cover the dough in plastic wrap and refrigerate it for 24 hours to develop flavor; otherwise, scoop the dough onto parchment-lined or silicone baking mats placed on light-colored baking sheets to avoid burning. Bake the cookies in the preheated oven for 8 to 11 minutes, watching for lightly golden edges. Once baked, let the cookies cool on the pan for 5 minutes before transferring them to a rack to cool fully.