Add the butter to a small saucepan and heat on medium until the butter is melted. Continue to cook, stirring often, until the butter begins to turn brown and smell nutty. Remove from heat and allow to cool and partially solidify in the refrigerator.
While the butter is cooling, mix together the flour, cream of tartar, baking soda, salt, cinnamon, ginger, cloves, and nutmeg together in a medium bowl. Set aside.
Add the butter and sugar to a stand mixer and beat until light and fluffy. Beat in the pumpkin puree, and the egg yolk, if needed. Mix in the vanilla.
Beat in the flour mixture and beat until just combined.
Cover the bowl and chill in the refrigerator. While the dough is chilling, preheat the oven to 350 degrees F. Line two baking sheets with parchment paper. Mix together the ingredients for the coating in a shallow bowl.
Roll balls of dough that are about two tablespoons big. Roll the dough in the coating mixture, then place them 2 inches apart on the baking sheets.
Bake each sheet for about 8 - 10 minutes, or until a light golden brown.
Store in an airtight container for up to a week.
*If you find your pumpkin puree has low moisture, you may need to add an egg yolk to the cookie dough to keep it from being too dry to work with.