In a bowl, mix together the melted butter, granulated sugar and brown sugar.
Add in the vanilla and pumpkin puree. Stir to combine.
Then add in the cinnamon, pumpkin pie spice, cornstarch, baking soda and flour. Stir until dough forms.
Cover the dough and refridgerate for at least 2 hours before baking (must do this because of the melted butter!).
Preheat the oven to 350 F and while oven heats, mix together the 1/2 cup sugar and 3 tsps cinnamon for rolling cookies. Scoop your cookie dough into 1 inch balls and roll each into the cinnamon sugar before placing on a baking tray.
Bake for 8-10 minutes in the oven once preheated.