In a large mixing bowl, place the melted butter, granulated sugar, brown sugar, vanilla extract, and eggs, and whisk to combine well.
Add the cornstarch, and whisk to combine. Then add the oat flour, baking soda, and salt, and mix to combine. The cookie dough will be very sticky and soft.
Add the chocolate chips and mix until they’re evenly distributed throughout the dough.
Cover the mixing bowl and place it in the refrigerator to chill for at least 45 minutes or until very firm. The longer you chill the dough, the easier it will be to portion and handle. I have chilled it for as long as 4 days with great results.
When you are nearly ready to bake the cookies, preheat your oven to 350°F. Line rimmed baking sheets with unbleached parchment paper and set them aside.
Once the dough is chilled, scoop the dough into pieces of about 2 tablespoons each. A #40 spring loaded cookie/ice cream scoop is ideal for this purpose. For more uniform cookies, roll each tightly into a ball between your palms.
Place the pieces of cookie dough about 2-inches apart on the prepared baking sheets. For slightly thicker cookies, roll the cookie dough into balls between your palms and return them to the baking sheet.
Place the baking sheets, one at a time, in the center of the preheated oven. Bake just until the balls of dough have melted and spread, the cookies are brown around the edges and are mostly set in the center (about 12 minutes).
Remove the baking sheet from the oven.
If any of the cookies have lost their shape during baking, as soon as you take them out of the oven place a large round cookie cutter, at least 1/4-inch larger than the cookie itself, around each cookie and move it around in concentric circles to coax the still hot cookie into shape.
Allow the cookies to cool completely on the baking sheet so they are stable before you move them. It should take 10 to 15 minutes.
Video
Notes
The how-to video for this recipe has been modified slightly to reduce the amount of cornstarch for a better-tasting cookie.Nutrition information is an estimate, per cookie, and should not be relied upon.