Beat butter with electric mixer on medium speed. Add sugar and pumpkin. Beat until fluffy. Add cream of tartar, salt and baking soda. Mix well.
Add vanilla and egg. Beat until well mixed. Add flour in 3 increments, beating until just incorporated. Cover dough with plastic wrap and chill for 1 hour.
Mix topping ingredients on a Chinet® plate.
Preheat oven to 350 degrees F.
Remove dough from refrigerator. Roll into 1 1/2" balls. Roll balls in sugar topping, covering all sides.
Place on cookie sheet 2 inches apart. Bake 12-14 minutes. Allow cookies to cool 5 minutes, then transfer to cooling rack.