In a medium bowl, whisk flour, cinnamon, baking soda, and salt. Set aside.

In the bowl of an electric mixer, beat butter and sugars on med-high until pale and fluffy (approx. 3 minutes).

Add eggs one at a time, fully incorporating after each addition, and beat on high for 1 minute. Add vanilla.

Turn mixer to low and add flour mixture, mix until combined.

Add oats and chocolate chips. Mix until just combined.

Chill dough in the fridge for an hour (optional, but yields better results).

Preheat oven to 350F and line a baking sheet with parchment or a Silpat.

Using a small cookie scoop, place cookies on baking sheet 2" apart. I did 11 cookies per sheet.

Bake for 10mins or until edges are lightly browned but center is still soft and unset.

Cool for 5 minutes on baking sheet, then transfer to cooling rack to cool completely.