Add flour, oats, salt, baking soda, and ground cinnamon to a bowl. Whisk to combine.
Melt the butter in a medium bowl.
Add dark brown sugar and granulated sugar and mix until combined.
Add vanilla extract and egg. Mix until combined.
Add flour mixture into butter mixture and stir until just combined.
Fold in the raisins until evenly distributed.
Cover the bowl and place in refrigerator for 30 minutes.
Scoop out 12 cookies using a #20 (3 tablespoon) cookie scoop. Cover and refrigerate cookies for 2 hours.
Preheat oven to 325° F. Line a baking sheet with parchment paper. Bake for 13-14 minutes.
Remove from the oven and let cool on baking sheet for 10 minutes before transferring to a wire rack to cool completely.