Preheat the oven to 350 degrees. Spray a 9x9 pan with non stick spray and line it with parchment paper.
Add the butter to a pot and heat it over medium heat. Allow the butter to melt and come to a simmer. Simmer until the butter is giving off a nutty scent and has browned. The whole process should take about 5 minutes. Remove the butter from the heat and allow it to cool until it's room temperature but still liquid.
1 ¼ cups (280 g) unsalted butter
Then dry your pumpkin. This may seem weird but it is the only way these blondies will bake properly and not turn out cakey! Spread your pumpkin on a plate and place a paper towel over the top. Lightly press to absorb the liquid. Repeat the step at least five more times. (It needs to reduce down to ⅓ cup from ¾ cup). Set aside.
¾ cup (183 g) canned pumpkin puree
In a medium bowl, whisk together the flour, pumpkin pie spice, baking soda, baking powder and salt. Set aside the flour mixture.
2 ½ cups + 2 tablespoon (329 g) all-purpose flour, spooned and leveled, 1 ½ tablespoon pumpkin pie spice, ¾ teaspoon baking powder, ¾ teaspoon baking soda, ¾ teaspoon salt
To a large bowl add the brown butter, brown sugar, egg yolks, vanilla and pumpkin puree and mix with a hand mixer on medium speed until combined and smooth. (You can also use a stand mixer with a paddle attachment.)
1 ½ cups (330 g) light brown sugar, 3 egg yolks, 1 tablespoon (15 ml) vanilla
Add in the dry ingredients to the wet ingredients and combine on low speed.
Fold in the white chocolate chips with a rubber spatula.
½ cup (100 g) white chocolate chips
Press the dough into the prepared pan.
Mix the granulated white sugar and pumpkin pie spice together in a small bowl. Sprinkle it over top of the blondies.
2 tablespoon (25 g) granulated white sugar, ¼ teaspoon pumpkin pie spice
Bake the blondies for 26-28 minutes until the center is slightly puffy and a toothpick comes out from the center with just a few moist crumbs.
Let the blondies cool in the pan for 15 minutes, then sprinkle extra white chocolate chips over the top if you wish. Then let the blondies cool completely.
Remove the blondies from the pan and cut into 16 squares. Then enjoy!