Make the Egg Substitute: Whisk together the cornstarch and water until the cornstarch is dissolved.
Make the Cookie Dough: Cream the softened butter in a large bowl, with a hand mixer on high speed. Add the sugars & mix until well creamed together with the butter, at least 1 minute. Add the vanilla and cornstarch egg substitute and mix until well combined, about 1 minute, on medium speed.
1 cup salted butter, softened at room temperature , 3/4 cup brown sugar, packed, 3/4 cup granulated sugar, 1 and 1/2 tsp vanilla extract , 2 tbsp corn starch , 1/4 cup + 2 tbsp warm water
Finish the Dough: Add the dry ingredients and mix until a dough forms (it may be a bit crumbly at first, but keep mixing until it comes together). Add the chocolate chips and mix on low speed to distribute evenly.
2 and 2/3 cups all-purpose flour, spooned & leveled, 1 tsp baking soda, 1/4 tsp salt, 2 cups semi-sweet chocolate chips
Form into Balls & Chill the Dough: Make dough balls about 80 grams each. Place in an airtight container to chill in the fridge for at least 2 hours or up to 24, or in the freezer just until solid. You can make smaller dough balls if desired. Bake the Cookies: Preheat your oven to 350° F. Line a few cookie sheets with parchment paper or silicone baking mats. Place about 5-6 cookie dough balls on a sheet, leaving room for them to spread. Bake for 10-13 minutes. The centers of the cookies will look a tad underdone, but the edges should be set when gently tapped, and will have a tinge of light golden brown. They'll set up to the perfect soft-baked texture as they cool.If the cookies aren't baked after 10-13 minutes, simply add a bit more time until they appear done based on the cues given above. Serve + Store: Let cookies cool on the pan placed on a wire rack, until they're not too hot, then dig in while they're warm! Store cooled cookies in an airtight container for 3-4 days or longer in the fridge. Re-warm in the microwave or oven for warm, gooey perfection.
Freezing Cookie Dough: Once you've got your dough scooped into balls, freeze on a baking sheet, covered with a clean kitchen towel. Once solid, transfer to an airtight freezer-safe container or bag. Cookies can be stored this way for about 2-3 months, and can be baked straight from frozen! Follow the baking directions as listed above.