Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper.

In a large mixing bowl, whisk together the rolled oats, all-purpose flour, baking powder, cinnamon, nutmeg, and salt.

In a separate bowl, beat together the softened butter and brown sugar until fluffy. Mix in the pumpkin puree and eggs, then stir in the vanilla extract.

Slowly incorporate the dry mixture into the wet ingredients, mixing gently until just combined.

Scoop the dough into rounds and place on prepared baking sheets, spacing them about two inches apart.

Bake for 12-15 minutes, or until edges are golden brown. Let cool on wire racks.

Prepare the icing by mixing powdered sugar with milk until smooth. Drizzle over cooled cookies.