In a stand mixer or large bowl, cream together the softened butter, pumpkin puree, brown sugar, granulated sugar, and vanilla until light and fluffy.

In a separate large bowl, whisk together the all-purpose flour, baking powder, pumpkin pie spice, cornstarch, and salt.

Gradually add the dry ingredients to the wet ingredients bowl, mixing on low speed until just combined.

Cover the bowl and place it in the fridge for 30 minutes or overnight.

Preheat the oven to 350 °F (177 °C).

Scoop 2-inch balls of dough and flatten into disks on a parchment-lined baking sheet.

Bake on the center rack for 10-12 minutes until edges turn light golden brown.

Let them cool completely on the baking sheet.

In a medium bowl, whip together all frosting ingredients until fully combined.

Spoon icing into a piping bag fitted with a piping tip and pipe the cinnamon frosting onto cooled cookies.

Sprinkle pumpkin pie spice on top and enjoy!