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

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

Beat in the eggs one at a time, ensuring each is fully incorporated. Stir in the vanilla extract for a rich, aromatic flavor.

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

Gently fold in the rolled oats and your choice of raisins or chocolate chips. This step ensures even distribution of ingredients for the best texture and flavor.

Drop rounded tablespoons of dough onto the prepared baking sheets, spacing them about 2 inches apart. Bake in the preheated oven 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.