Whisk flour, cinnamon, baking soda, and salt together in a bowl; set aside
In the bowl of a stand mixer with paddle attachment, beat the butter on medium speed until smooth, 1 minute; add the brown sugar and granulated sugar; beat on medium-high speed until creamed, 2 minutes
Add the eggs, molasses, and vanilla; beat on high speed until combined, 1 minute; scrape down the sides and bottom of bowl; beat again as needed to combine
Add the dry ingredients to the wet ingredients; mix on low until combined; with the mixer on low speed beat in the oats and chocolate chips; dough will be thick and sticky; cover and chill the dough for 45 minutes
Preheat oven to 350F; line baking sheet with parchment paper; set aside
Scoop cookie dough, 3 tablespoons per cookie; place on baking sheets; bake for 13-14 minutes until lightly browned on the sides
Remove and allow to cool for 5 minutes before transferring to wire rack