In a large mixing bowl cream together butter, brown sugar, granulated sugar, and pumpkin spice.
Add egg and vanilla, and blend until light and fluffy.
Add flour, baking soda, cream of tartar and salt. Mix until just combined. Dough will be thick.
Using a 1 Tablespoon scoop, drop dough by scoopful onto parchment paper. Roll into balls, set in freezer for 15 minutes.
Preheat oven to 350˚F.
Combine sugar and pumpkin spice in a small bowl. Roll chilled dough in spiced sugar, and place on baking sheet at least 2 inches apart.
Bake for 8-9 minutes. Cookies will look puffed up, but will flatten when cool.
Cool on baking sheet for 2 minutes. Transfer to baking rack to cool completely.