Place the pumpkin puree in a small saucepan over medium heat. Cook, stirring frequently, for about 5-7 minutes until it reduces to about ½ cup and becomes darker and thicker. Transfer to a plate and spread it out to cool completely.
Whisk together the flour, baking soda, baking powder, salt, cinnamon, ginger, nutmeg, and cloves in a medium bowl.
In a large bowl, beat the softened butter, brown sugar, and granulated sugar together until light and fluffy, about 3-4 minutes.
Beat in the cooled pumpkin puree, egg, and vanilla extract until well combined.
Gradually add the dry ingredients to the wet ingredients, mixing on low speed just until combined.
Gently fold in the chopped pecans and white chocolate chips (if using).
Cover the dough and refrigerate for at least 30 minutes, or up to 24 hours.
Preheat your oven to 350°F and line baking sheets with parchment paper.
Scoop rounded tablespoons of dough, place them 2 inches apart, and gently flatten each cookie slightly with your palm. Press a few extra pecan pieces on top of each cookie.
Bake for 12-14 minutes, or until the edges are set but the centers still look slightly underdone.
Allow cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.