Over medium-low heat, melt unsalted butter in a light-colored saucepan, stirring frequently until it foams. Increase the heat to medium, allowing the butter to caramelize and turn a golden brown, which should take about 5-7 minutes.

In a large bowl, whisk together the cooled brown butter, light brown sugar, white sugar, maple syrup, egg yolk, vanilla extract, and pumpkin puree until the mixture is smooth and well incorporated.

In a separate bowl, whisk together the all-purpose flour, baking powder, baking soda, kosher salt, pumpkin pie spice, and ground cinnamon until evenly mixed.

Gently fold the dry ingredients into the wet mixture using a spatula or wooden spoon, mixing until just combined. Cover the bowl with plastic wrap and chill the dough in the fridge for at least 30 minutes.

While the dough is chilling, preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.

After chilling, scoop the dough into rounded balls, each about two tablespoons full. Roll each ball in the pumpkin pie sugar mixture and place the dough balls on the prepared baking sheets, spaced about 3-4 inches apart.

Place the baking sheets in the preheated oven and bake the cookies for 10-14 minutes or until the edges look set while the centers remain slightly underbaked.

Once baked, remove the cookies from the oven and let them cool on the baking sheets for 5 minutes before transferring to a wire rack to cool completely.