Whisk flour, cinnamon, baking soda, and salt together in a medium bowl.
Cream butter and both sugars in a large bowl with an electric mixer, 2 to 3 minutes. Beat in eggs, one at a time, then mix in vanilla. Gradually mix in dry ingredients, with oats last, until well combined. I like to roll the dough into balls, then chill dough in the refrigerator for at least 1 hour.
Preheat the oven to 375F (190C). Put parchment paper on the tray. Place the chilled dough balls 2 inches apart on the prepared cookie sheets. Very gentle press them.
Bake in the preheated oven until light golden brown around the edges. Let cookies to cool on baking sheet for 5 minutes before transferring to a wire rack to cool completely. Enjoy!