Preheat the oven to 350°F (177°C). Line two large baking sheets with parchment paper or silicone baking mats and set aside.
In a medium-sized mixing bowl, whisk together the flour, cinnamon, baking soda, and salt. Stir in the old-fashioned rolled oats and set aside.
In the bowl of a stand mixer fitted with the paddle attachment, or in a large mixing bowl using a handheld mixer, beat the butter, light brown sugar, and granulated sugar together for 1-2 minutes or until well combined.
Mix in the egg and vanilla extract, stopping to scrape down the sides of the bowl as needed.
Add the dry ingredients and mix on low speed until just combined, then mix in the chocolate chips on low-speed until fully incorporated into the cookie dough. Cover tightly and refrigerate for at least 30 minutes.
Using a 1.5 tablespoon cookie scoop, scoop the dough onto the prepared baking sheets, making sure to leave a little room between each one. Gently press down each ball of cookie dough to slightly flatten them.
Bake at 350°F (177°C) for 10-13 minutes or until the tops of the cookies are set.
Remove from the oven and cool on the baking sheet for 5-10 minutes, then transfer the cookies to a wire rack to cool completely.