Preheat your oven to 350 degrees and line a baking tray with parchment paper or spray with non-stick spray.
In a large bowl, combine butter, sugars and eggs until thoroughly mixed. Mix in the pumpkin. In a separate bowl, combine flour, cream of tartar, baking soda, baking powder, spices and salt.
Slowly add the dry ingredients to the butter mixture in small increments, mixing completely until all has been incorporated.
Refrigerate your cookie dough for 20-30 minutes
Once your dough has chilled, combine the last 3 tablespoons of sugar and cinnamon in a small bowl.
Roll dough into 1 inch balls and then roll through the cinnamon sugar to fully coat before placing them on a cookie sheet prepared with nonstick spray or lined with parchment paper. Flatten the cookies slightly as they will not spread much.
Bake for 9 minutes... no more, no less.
Remove from oven and let cool for 5 minutes before transferring the cookies to a cooling rack.Once completely cool, move cookies to an airtight container or zip top bag.