Preheat oven to 400F. Spray a large cookie sheet with nonstick cooking spray.
In a stand mixer, with the paddle attachment, add the butter. Whip until smooth.
Then, add in the sugars. Beat to combine.
Add in the vanilla and eggs. Beat to combine.
Then, in a large bowl, add the cinnamon, salt, baking soda, cornstarch, flour, and oats. Whisk to combine.
Pour dry ingredients into stand mixer. Beat to combine.
Add in the diced peaches. Fold into the batter using a silicone spatula.
Use a cookie scoop to portion dough onto baking sheet.
Bake for 10 minutes.