Step 1: Prepare the Dough

1. Cream Butter and Sugars: In a large mixing bowl, beat the softened butter, granulated sugar, and brown sugar together until light and fluffy, about 2-3 minutes. This step helps create a soft and chewy cookie texture.
2. Add Pumpkin and Egg Yolk: Add the pumpkin puree, egg yolk, and vanilla extract to the butter mixture, and mix until well combined. The egg yolk adds richness, while the pumpkin brings moisture and a subtle flavor.
3. Combine Dry Ingredients: In a separate bowl, whisk together the flour, cream of tartar, baking soda, salt, cinnamon, nutmeg, and ginger. These spices give the cookies their warm, autumnal flavor.
4. Mix Wet and Dry Ingredients: Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Be careful not to overmix, as this can make the cookies tough.

Step 2: Prepare the Cinnamon-Sugar Coating

1. Mix Cinnamon and Sugar: In a small bowl, combine the granulated sugar and cinnamon for the coating. Set aside.

Step 3: Shape and Coat the Dough Balls

1. Portion the Dough: Use a cookie scoop or tablespoon to portion out rounded tablespoons of dough. Roll each portion into a ball.
2. Coat in Cinnamon-Sugar: Roll each dough ball in the cinnamon-sugar mixture, ensuring it is fully coated. This coating adds a classic snickerdoodle flavor and a slight crunch to the edges.

Step 4: Bake the Cookies

1. Preheat the Oven: Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper or a silicone baking mat.
2. Arrange on Baking Sheet: Place the cinnamon-sugar-coated dough balls on the prepared baking sheet, spacing them about 2 inches apart to allow for spreading.
3. Bake: Bake in the preheated oven for 10-12 minutes, or until the edges are set and the tops look slightly cracked. The centers should still be soft, as the cookies will firm up as they cool.
4. Cool on Wire Rack: Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.