In a stand mixer, beat together vegan butter, pumpkin purée, brown sugar, and granulated sugar on medium speed for 3-5 minutes until light and fluffy. Add vanilla extract and mix well.

In a separate bowl, whisk together all-purpose flour, baking powder, pumpkin pie spice, cornstarch, and salt. Break any clumps for an even mixture.

Gradually add the dry mixture to the wet ingredients in the stand mixer. Mix on low speed until just combined, maintaining a soft dough consistency.

Cover the bowl with plastic wrap or a kitchen towel and refrigerate the dough for at least 30 minutes.

Preheat your oven to 350°F (175°C). Once chilled, scoop the dough into 2-inch balls, flatten slightly, and place them on a parchment-lined baking sheet.

Bake the cookies for 10-12 minutes until edges are set while centers remain soft. They will firm up as they cool.

In a mixing bowl, beat together vegan butter, vanilla extract, cinnamon, pumpkin pie spice, and powdered sugar until smooth and creamy.

Once cookies are completely cooled, frost each cookie with the cinnamon frosting, adding a sprinkle of pumpkin pie spice if desired.