In a medium bowl, cream together the butter, sugar and brown sugar until the mixture is creamy. Add in the pumpkin purée and stir until combined.
Stir in the egg yolk and vanilla extract.
Combine the flour, baking soda, cream of tartar, salt and pumpkin pie spice in a different bowl.
Gradually add the dry ingredients into the butter mixture until well combined.
Cover and refrigerate for at least 45 minutes.
Preheat the oven to 350 degrees Fahrenheit.
In a small bowl, stir together the 2 tablespoons of sugar, and the cinnamon.
Roll dough into 1 1/2 tablespoon sized balls, then roll the balls in the cinnamon-sugar.
Place them onto a cookie sheet and bake for 10-12 minutes until the edges should be slightly brown. The center of the cookies will still appear soft.
Let the cookies rest on the baking sheet for 10 minutes. Then move to a wire rack to cool completely.
Then the cookies are ready to serve and enjoy!