### Instructions
1. **Preheat & Prep:** Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper.
2. **Cream Butter & Sugars:** In a large bowl, cream together the softened butter, brown sugar, and granulated sugar with an electric mixer until light and fluffy (about 2-3 minutes).
3. **Add Wet Ingredients:** Beat in the eggs one at a time, incorporating each fully before adding the next. Stir in the vanilla extract until combined.
4. **Combine Dry Ingredients:** In a separate medium bowl, whisk together the flour, baking soda, salt, and ground cinnamon.
5. **Combine Wet & Dry:** Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Do not overmix.
6. **Stir in Oats:** Fold in the old-fashioned rolled oats until evenly distributed throughout the dough.
7. **Scoop & Bake:** Drop rounded tablespoons of dough onto the prepared baking sheets, leaving about 2 inches between cookies.
8. **Bake:** Bake for 10-12 minutes, or until the edges are golden brown and the centers are still soft.
9. **Cool:** Let the cookies cool on the baking sheets for a few minutes before transferring them to a wire rack to cool completely.
### Short Tips
* **Don’t Overmix:** Overmixing the dough can lead to tough cookies. Mix until just combined.
* **Room Temperature Butter:** Ensure your butter is truly softened (but not melted!) for the best creamy texture.
* **Old-Fashioned Oats:** Use old-fashioned rolled oats, not instant, for the best chewy texture.
* **Storage:** Store cooled cookies in an airtight container at room temperature for up to 3-4 days. They also freeze well.
* **Optional Add-ins:** Feel free to add 1/2 cup of raisins, chopped walnuts, or white chocolate chips for extra flavor and texture!
