Preheat the oven to 350°F. Line baking sheets with parchment paper or lightly grease them.
Combine the dry ingredients. In a medium bowl, whisk together the flour, oats, pumpkin pie spice, baking soda, cinnamon, and salt.
Cream the butter and sugars. In a large mixing bowl, beat the softened butter, brown sugar, and granulated sugar until light and creamy.
Add the wet ingredients. Beat in the pumpkin puree, egg, and vanilla until well combined.
Combine the dough. Gradually add the dry ingredients to the wet ingredients, mixing just until combined.
Add the pecans and raisins. Gently fold them into the cookie dough.
Scoop the cookies. Drop the dough by rounded tablespoons onto the prepared baking sheets, leaving space between each cookie.
Bake for 12–15 minutes, or until the cookies are set and lightly golden around the edges. Allow them to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.