Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking dish or line it with parchment paper.

In a large mixing bowl, combine melted unsalted butter with both light brown sugar and granulated sugar. Whisk together until smooth and creamy.

Add eggs one at a time, whisking thoroughly after each addition. Blend in vanilla extract and pumpkin puree until well incorporated.

In a separate bowl, whisk together all-purpose flour, baking soda, salt, ground cinnamon, nutmeg, ginger, and cloves.

Gradually add the dry ingredients into the wet ingredients, stirring gently until just combined.

Fold in the white chocolate chips and chopped pecans (if using).

Pour the batter into the prepared baking dish, spreading it evenly.

Bake for 30-35 minutes, checking for doneness with a toothpick. It should come out with a few moist crumbs.

Remove from oven and cool for about 20 minutes in the pan before transferring to a wire rack to cool completely. Slice into squares.