Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper.
In a large bowl, cream butter, brown sugar, and granulated sugar together until light and fluffy (about 2–3 minutes).
Beat in the eggs one at a time, followed by vanilla extract.
Stir in flour, baking soda, cinnamon, and salt just until combined—don’t overmix.
Fold in oats and chocolate chips until evenly distributed.
Scoop dough into rounded balls (about 1.5 tbsp each) and place on the prepared baking sheet 2 inches apart.
Bake for 10–12 minutes or until edges are lightly golden and centers still look slightly underdone.
Let cool on the baking sheet for 5 minutes before transferring to a wire rack.