1. Preheat oven to 350°F (175°C) and line baking sheets with parchment paper

2. Whisk together oats, flour, baking soda, cinnamon, nutmeg, and salt in a medium bowl

3. Beat butter, brown sugar, and granulated sugar until light and fluffy

4. Mix in pumpkin purée, egg, and vanilla until smooth

5. Fold dry ingredients into wet ingredients until just combined

6. Stir in optional add-ins if using

7. Scoop tablespoonfuls of dough onto prepared sheets, spacing 2 inches apart

8. Flatten tops slightly with the back of a spoon

9. Bake for 10–12 minutes until edges are golden and centers are set

10. Let cookies cool on baking sheet for 5 minutes, then transfer to a wire rack