Preheat the oven to 350 F (177 C). Line a 9 x 9 (23 cm) pan with parchment paper along the bottom and two sides. Make the brown butter and remove the excess moisture from the pumpkin puree. In a sauce pan or pot, melt the butter on low heat until the butter to begins to foam. Once it starts to foam, whisk or stir the liquid butter frequently. The butter will begin to smell nutty and very fragrant. Once the foam has subsided, the butter should have some brown, lightly toasted bits floating at the bottom. Pour the brown butter in a heat safe bowl to cool for about 20 minutes to room temperature. 10 tablespoons (141 g) unsalted butter, cubed
Remove the excess moisture from the pumpkin. Line a medium sized bowl with a 4 layers of paper towels. Measure out 1 cup (260 g) pumpkin puree onto the paper towels. Allow the pumpkin puree to sit on the paper towels for about 5 - 10 minutes. Gather the paper towels and gently squeeze out the excess moisture. Some moisture will still remain in the pumpkin puree. The puree should reduce down to about ½ cup (130 g) and feel tacky, not wet.
1 cup (260 g) canned pumpkin puree
In a large mixing bowl, whisk in the cooled brown butter with the light brown until well combined. Whisk in the blotted pumpkin puree, egg, yolk and vanilla extract until smooth and well combined. Set aside for now.
1¾ cup (350 g) light brown sugar, 1 large egg, room temperature, 1 large egg yolk, room temperature, 1 tablespoon (15 ml) vanilla extract
In another mixing bowl, whisk the flour, baking powder, baking soda, pumpkin spice and salt together until well combined. Stir the dry ingredients into the wetuntil just combined. I like to do this about ½ of the dry ingredients at a time. If using any mix ins like white chocolate chips, mix them in now.
2¾ cup (330 g) all purpose flour, 2 teaspoons pumpkin spice, ¾ teaspoon baking soda, ¾ teaspoon baking powder, ½ - 1 cup (85 - 170 g) white chocolate chips
Smooth the blondies batter into the prepared pan. Use a flexible spatula to smooth the blonde brownie batter evenly across the pan.If you would like to top the blondies with a spiced sugar, whisk the sugar and pumpkin spice together until well combined. Top the blondies with the spiced sugar. 2 tablespoons (25 g) granulated sugar, ¼ teaspoon pumpkin spice
Bake for about 25 - 30 minutes or until the sides of the chocolate chip blondies are firm and set and the top is crisp with some cracks forming across the top. Cool the buttery pumpkin blondie bars in the pan to room temperature, slice and enjoy!