In the bowl of a stand mixer, combine the melted butter, sugar and brown sugar with the paddle attachment. Cream for about 30 seconds or until combined. Add in the vanilla and pumpkin and beat to combine. Lastly, add in the cinnamon, pumpkin pie spice, cornstarch, baking soda and flour and beat gently until a soft dough forms.
Refrigerate the dough, covered, for at least 2 hours or until sufficiently chilled. Chilling is mandatory.
Preheat oven to 350 degrees F. In a small bowl, whisk together the sugar and cinnamon. Drop rounded Tablespoon-sized balls of dough into the cinnamon sugar mixture and toss to coat. Place 1-2" apart on a silicone or parchment lined baking sheet.
Bake for approx. 8-10 minutes, rotating pans halfway through baking time to ensure even cooking. Cool completely on the sheets before dusting with any remaining cinnamon sugar topping.