In your stand mixer fitted with a paddle attachment, add the butter and sugars. Cream for 2-3 minutes or until they are fully incorporated and fluffy.
Add in the eggs and vanilla and mix until combined.
Turn the mixer off and add in the flour, oats, baking soda, and cinnamon.
With the mixer on low, mix until just combined.
Refrigerate for 30 minutes, or up to overnight.
When you are ready to bake the cookies, preheat oven to 350°F and prepare a baking sheet by lining it with parchment paper.
Use a cookie scoop (Mine holds about 1 1/2 tablespoons of batter) and drop dough onto the parchment-lined baking sheet about 2 inches between.
Bake for 8-10 minutes or until the edges are lightly golden. The top of the cookie may appear a little wet, but they will continue to bake out of the oven. You don't want the cookies raw, so make sure they bake for at least 8 minutes.
After allowing the cookies to slightly cool, move them to a cooling rack.