In a stand mixer or large bowl, cream together the softened butter, pumpkin puree, brown sugar, granulated sugar, and vanilla until the mixture is 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 (don’t over-mix).

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 using a cookie scooper or a large spoon and press down to flatten into disks.

Arrange them a couple of inches apart on a parchment-lined baking sheet.

Bake on the center rack for 10-12 minutes. Let them cool completely on the baking sheet.

In a medium bowl, use an electric mixer or stand mixer with whisk attachment to whip together all the frosting ingredients until fully combined.

If preparing in advance, cover with plastic wrap and refrigerate until ready to use.

Spoon icing into a piping bag fitted with Wilton Piping Tip #2A, and pipe the frosting on top of the cooled cookies in a swirl.

Sprinkle pumpkin pie spice on top, and enjoy!