Preheat the oven to 350º F. Line a cookie sheet with a silicone baking mat or parchment paper.

In a mixing bowl combine the flour, cornstarch, baking soda, salt, and chocolate chips. Set aside.

In a separate mixing bowl, combine the butter, brown sugar, and granulated sugar. Beat on medium speed for 1 minute. You want this mixture to be fluffy and pale in color.

Add in the egg yolk and vanilla extract, beat for 30 seconds.

Gradually mix in the dry ingredients, mixing on low speed. The dough will be thick. I like to finish mixing the flour into the dough by hand with a spatula.

Use a cookie scoop to form golf ball sized cookie dough balls, roll into a smooth ball between your hands. Press extra chocolate chips on the outside of the dough balls. Place the cookies on a cookie sheet lined with a silicone baking mat at a time.

For the cookies in the photos, the dough balls were about 3 heaping tablespoons (golf ball sized), so that’s a large cookie! I baked those for 13-15 minutes – just until the edges of the cookies would begin to turn firm up and brown slightly. The result is a soft and chewy cookie! If you make smaller dough balls, you should reduce the baking time since the baking estimates are for golf ball sized dough balls.

Baking time estimates for regular sized dough balls (2 tbsp of dough) bake for 9-13 minutes. Allow the cookies to cool for 15 minutes on the baking sheet before removing.