1. In the bowl of an electric mixer, cream together butter and sugars on medium speed. Add pumpkin puree and mix until well smooth and creamy.
2. Mix in eggs, one at a time, then add vanilla and mix.
3. In another bowl, whisk together flour, baking soda, cream of tarter, salt and pumpkin pie spice.
4. On low speed, gradually add the dry ingredients to the wet ingredients on low speed. Mix until everything is incorporated into the dough.
5. Cover and chill the dough for 2-3 hours.
6. Preheat oven to 350 degrees.
7. Roll the dough into 1 1/2 tablespoon sized balls and place them on a baking sheet. I like to line my baking sheets with a Silpat baking mat or parchment paper to prevent sticking and to help them bake evenly.
8. Bake for 9-10 minutes, and then cool for a few minutes on the baking sheet before placing them on a cooling rack to cool completely.

For the Frosting

1. In a medium bowl, whisk together your softened butter, softened cream cheese, and powdered sugar. Then whisk in the Greek yogurt and maple extract. Start out with 1/4 teaspoon and then taste the frosting. If you like the flavor stronger, add another 1/4 teaspoon. When your cookies are completely cooled, spoon and spread the frosting over each cookie.
2. If you want to stack the frosted cookies when you store them, first chill them to set the frosting, and then place sheets of parchment paper in between the layers to keep them from sticking together.