Start by melting ½ cup unsalted butter and setting it aside to cool. While that’s cooling, place ⅔ cup pumpkin puree in a bowl and squeeze out as much moisture as you can with some paper towels and drain the bowl as you go. Reduce the puree by roughly half until you have ⅓ cup remaining and set aside.

In a mixing bowl, add 1 ¾ cups of all-purpose flour, 1 teaspoon baking soda, 1 teaspoon cream of tartar, ½ teaspoon salt, 1 ½ teaspoons of ground cinnamon, and 1 teaspoon of pumpkin pie spice. Whisk together and set it aside.

In another mixing bowl, add the cooled, melted butter with ½ cup granulated sugar, ⅓ cup brown sugar, the reduced pumpkin puree, the egg yolk, and 1 teaspoon of vanilla extract. Whisk together until fully combined and there’s no streak of egg or pumpkin remaining.

Add a little bit of the dry mixture into the wet mixture and whisk until just barely combined, then add more of the dry mixture. Repeat this process in 3-4 increments until there’s no dry pockets of flour remaining. Cover the mixing bowl and place in the fridge to chill for at least 30-45 minutes.

When the dough is almost done chilling, preheat the oven to 350°F / 177°C and line two baking sheets with parchment paper or a silicone baking mat. In a bowl, combine the ¼ cup of white sugar and 1 teaspoon of ground cinnamon.

Using a 1 ½ tablespoon cookie scoop, scoop out some dough and roll it into a ball in your hands. Roll the dough through the cinnamon sugar mixture and place on a baking sheet about two inches apart, then gently press the cookies down slightly. Return the dough to the refrigerator between batches.

Bake for 10-12 minutes, then allow to cool for about 5-10 minutes on the baking sheet before moving to a cooling rack. Err on the side of the cookies looking a bit underbaked. They will set as they cool, and slightly underbaking will help keep them soft and chewy once cooled.