Line a large plate with a few paper towels. Spread on the pumpkin puree, top with more paper towels, and gently press the towels down so they absorb the excess moisture. Repeat this process once or twice, changing the towels each time, until the pumpkin has thickened and measures ⅓ cup.
Preheat the oven to 350°F. Line an 8 x 8-inch baking dish with parchment paper and then spray non-stick cooking spray or grease with butter.
In a large mixing bowl, whisk the reduced pumpkin purée, melted butter, brown sugar, sugar, egg, egg yolk, and vanilla extract until smooth.
In a small mixing bowl, stir the flour, cornstarch, salt, baking powder, baking soda, pumpkin pie spice blend, and ground cinnamon until well combined.
Add the dry ingredients to the wet ingredients and stir in until just combined.
Add all but 2 tablespoons of the white chocolate chips and stir until the chips are just distributed throughout.
Pour the batter into the prepared baking pan and gently spread it out into the sides, creating an even layer. Sprinkle the remaining 2 tablespoons of chips on top. Bake for 22-25 minutes or until a toothpick inserted into the center of the blondies comes out with just a few moist crumbs.
Cool the pan of blondies on a wire cooling rack for at least 15-20 minutes before serving at your preferred temperature. Enjoy!
Notes
Storage Directions
Storing: Once cooled completely to room temperature, store the blondies in an airtight container at room temperature for up to 3 days or in the refrigerator for up to 5 days.
Freezing: Transfer cooled bars to a freezer-safe container, placing small sheets of parchment paper between them to prevent sticking, and freeze for up to 2 months. Defrost at room temperature for 30-60 minutes until thawed.
Reheating: For that fresh-from-the-oven feel, microwave a blondie on a plate for 10–15 seconds until just warmed through. So gooey and good!
Recipe Pro-Tips
Reduce the pumpkin puree – Don’t skip this step! Removing moisture concentrates the pumpkin flavor and ensures the blondies stay dense and fudgy, not cakey.
Use room-temperature eggs – This helps everything blend smoothly and evenly.
Let them cool before slicing – For clean edges and the best fudgy texture, give the blondies at least 20 minutes to cool.
Don't overmix – Gently fold the dry ingredients into the wet until just combined to avoid tough bars.
Underbake slightly – A slightly gooey center will continue to set as the bars cool. The toothpick inserted into the center of the bars should have just a few moist crumbs.