Step 1: Preheat your oven to 350°F (175°C) and line an 8x8 inch baking pan with parchment paper, leaving an overhang on the sides for easy removal.
Step 2: In a large mixing bowl, whisk together the melted butter, brown sugar, and granulated sugar until well combined and smooth.
Step 3: Add the pumpkin puree, egg, orange zest, and vanilla extract to the butter mixture. Whisk vigorously until the batter for your pumpkin and orange zest blondies is fully emulsified.
Step 4: In a separate medium bowl, sift together the flour, cinnamon, ginger, cloves, and salt.
Step 5: Gradually fold the dry ingredients into the wet ingredients using a spatula. Mix until just combined, ensuring you don't overwork the batter for the pumpkin and orange zest blondies.
Step 6: If using, fold in the white chocolate chips. Spread the batter evenly into the prepared baking pan.
Step 7: Bake for 28-32 minutes, or until the edges are golden brown and a toothpick inserted into the center comes out with just a few moist crumbs.
Step 8: Allow the pumpkin and orange zest blondies to cool completely in the pan before lifting them out and slicing into squares.