Line 2 baking sheets with parchment paper. Set aside
In a medium bowl, combine flour, oats, baking soda, salt, and cinnamon. Set aside
In a medium-sized saucepan over medium heat, melt butter until it begins to turn an amber color (about 5-7 minutes). Make sure to watch the butter closely as it can change color very quickly
Remove butter from heat and immediately stir in both brown and granulated sugars. Mix until smooth and the sugars begin to dissolve
Place mixture in the fridge to chill for 10 minutes
Remove mixture from the fridge and mix in egg, egg yolk, and vanilla until combined
Stir the flour mixture into the butter mixture until combined
Stir in chocolate chips until combined throughout
Using an ice cream scoop, portion dough into balls and place on prepared baking sheets. Place in the fridge to chill for 30 minutes. While dough chills, preheat oven to 325 degrees
Once chilled, remove from fridge and bake in preheated oven for 12-16 minutes until lightly browned