Preheat oven to 350°F. Line cookie sheets with parchment paper. In a medium-sized bowl, combine all the dry ingredients: flour, baking soda, baking powder, salt, cream of tarter, cinnamon, pumpkin spice and nutmeg. Set aside.
In a large bowl, cream butter and sugar with an electric mixer for about 1 minute. Add in vanilla and egg and mix just until combined. Then add in the pumpkin and stir until combined.
Next add flour to pumpkin mixture and mix together just until combined. Fold in the white chocolate chips if desired and then cover bowl with plastic wrap. Place in the refrigerator for at least 15 minutes (it will help it not be as sticky when rolling).
In a small bowl, mix together the remaining sugar, cinnamon and pumpkin spice. Roll the dough into 1-inch balls and then roll into the sugar mixture. Then place the cookies on the pan about two inches apart.
Bake for 12-13 minutes, or until the edges are lightly golden. Remove from oven and allow cookies to cool for 1-2 minutes on the pan. Then place on a cooling rack to cool completely.
Pumpkin: I prefer to use Libby's pumpkin puree. I measure it out and then dump it on a paper towel and pat it to remove the moisture. If you don't remove the moisture they will be more cakey. Storage and freezer instructions: Allow to cool and then store in a covered container for up to 3 days. For freezing place in a zip top bag (remove as much air as you can) and freeze up to 3 months.Freezing dough: You can also freeze the dough balls dipped in sugar. Place on a baking sheet and freeze for 30 minutes. Then transfer to a zip top bag once they are hard. When ready to bake, place on baking sheet to thaw 30 minutes prior to baking. An additional 2 minutes may be needed for cooking.