In a saucepan, brown 0.75 cup unsalted butter over medium heat until golden and nutty, about 5-7 minutes. Transfer to a mixing bowl and cool for 10 minutes.

Add 0.33 cup pumpkin puree, 0.75 cup granulated sugar, 0.5 cup brown sugar, 1 egg yolk, and 2 teaspoons vanilla extract. Mix well.

In a separate bowl, whisk together 2.25 cups all-purpose flour, 0.5 teaspoon baking soda, 1 teaspoon cream of tartar, 2 teaspoons pumpkin pie spice, and 0.5 teaspoon salt.

Gradually mix the dry ingredients into the wet mixture until a soft dough forms. Cover and refrigerate for 30-45 minutes.

Preheat your oven to 350°F (175°C). In a small bowl, mix together 0.25 cup sugar and 1 tablespoon cinnamon.

Scoop tablespoon-sized portions of the dough, roll into balls, coat in the cinnamon-sugar mixture, and place on a parchment-lined baking sheet.

Bake for 10-12 minutes until the edges are set and the tops are slightly crackled. Allow to cool on the baking sheet for 5 minutes before transferring to a wire rack.