Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper or silicone baking mats to prevent sticking.

In a large mixing bowl, cream together the softened butter, brown sugar, and granulated sugar until light and fluffy.

Beat in the eggs one at a time, followed by the vanilla extract. Mix until well combined.

In a separate bowl, whisk together the flour, baking soda, salt, and cinnamon. Gradually add the dry ingredients to the wet mixture, mixing until just combined.

Stir in the rolled oats and raisins or chocolate chips (if using) until evenly distributed.

Using a cookie scoop or tablespoon, drop rounded mounds of dough onto the prepared baking sheets, spacing them about 2 inches apart. Bake for 10-12 minutes, or until the edges are golden brown and the centers look slightly underbaked.

Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.