Preheat oven to 350 degrees.
In a medium bowl, mix together the flour, oats, cornstarch, cinnamon, baking soda, and salt. Set aside.
In a small sauce pan over medium heat, melt the butter. Stir it regularly to ensure even melting.
Once the butter is melted, begin to stir it constantly. It will turn yellow, foam up and eventually begin to turn brown and smell nutty. Once it does this, remove it from the heat and pour into a large mixing bowl.
Into the butter, whisk in the sugars. Then, add in the egg and vanilla and stir until mixed.
Add the flour mixture in and stir until combined. Stir in the chocolate chunks
Line a cookie sheet with parchment paper and roll the cookies into balls and put them on the cookie sheet, pressing down VERY slightly. You want the balls to be higher than they are wide, so they don't spread everywhere and they are nice and chewy!
Bake for for 11-12 minutes, until the tops feel just set. The cookies will feel very underdone, but they cook a lot more on the pan when they are cooling!
Let them cool on the pan for 5 minutes and then GENTLY transfer to a wire rack to finish cooling.
Devour!