Cream together the butter, brown sugar, and white sugar until light and fluffy (approx. 3-5 minutes). Add the egg and vanilla extract and blend until smooth. Add the oat flour, baking soda, salt, cornstarch, cinnamon, and old-fashioned oats to bowl and beat to combine. Add the flour and blend until fully incorporated. Cover the bowl in plastic wrap and refrigerate for one hour. The cookies will spread if not refrigerated.
Heat the oven to 350 degrees. Scoop out approximately 2 oz of dough and place no more than 9 on a sheet pan at a time (this recipe will make approximately 14 cookies). Refrigerate the cookies again for 10 minutes.
Bake for 10-12 minutes until lightly browned on the edges. You want the cookies to be slightly under baked so they remain soft, chewy, and tender. Allow to cool and enjoy!
*To make your own oat flour, blend up oats in a food processor until it begins to resemble flour.
Note: Since everyone’s health history and nutritional needs are so different, please make sure that you talk with your doctor and a registered dietitian to get advice about the diet and exercise plan that‘s right for you.