Preheat your oven to 350°F (175°C). This ensures that the cookies bake evenly and rise properly.

In a large mixing bowl, cream together the softened butter, brown sugar, and granulated sugar using an electric mixer on medium speed until light and fluffy, about 2-3 minutes. This incorporates air into the mixture, which helps the cookies to be light.

Add the pumpkin puree, egg, and vanilla extract to the butter mixture. Beat until well combined. The pumpkin adds moisture and flavor to the cookies.

In a separate bowl, whisk together the rolled oats, all-purpose flour, baking soda, baking powder, cinnamon, nutmeg, and salt. This helps to evenly distribute the dry ingredients.

Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Be careful not to overmix, as this can lead to tough cookies.

Fold in the chocolate chips if using, ensuring they are evenly distributed throughout the dough.

Line a baking sheet with parchment paper to prevent sticking and make cleanup easier.

Using a tablespoon or cookie scoop, drop rounded tablespoons of dough onto the prepared baking sheet, spacing them about 2 inches apart.

Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden. The centers may look slightly underbaked, but they will firm up as they cool.

Remove the baking sheet from the oven and let the cookies cool on the sheet for 5 minutes before transferring them to a cooling rack to cool completely.