Preheat the oven to 350°F and line two baking sheets with parchment paper.

In a medium-sized bowl, whisk together the flour, pumpkin spice, baking soda, and salt.

In another large bowl, whisk together the melted butter and sugars until smooth. Add the pumpkin purée, egg yolk, and vanilla extract, and whisk again until well combined.

Add the dry ingredients to the wet ingredients and mix with a spatula until just combined. Add the oats and mix until just incorporated.

Using a 1.5 tablespoon spring-loaded cookie scoop, scoop a rounded amount of dough and place 2 inches apart on the prepared baking sheet. Lightly flatten the top of each cookie.

Bake for 10-12 minutes, or until the edges are just set and lightly golden.

Remove from the oven and allow to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.