Spread the pumpkin purée over several layers of paper towels. Place additional paper towels on top and gently press to absorb the excess moisture. Repeat with fresh paper towels as needed, until the pumpkin is noticeably thicker and measures approximately 100-110g. Set aside.

Preheat the oven to 350°F. Grease an 8x8-inch light-colored metal baking pan and/or line it with parchment paper, leaving an overhang on two sides.

In a large mixing bowl, whisk together the melted butter, brown sugar, and granulated sugar until smooth and glossy.

Add the egg, egg yolk, and vanilla. Whisk vigorously for 30-45 seconds, until the mixture is thick, smooth, and well combined.

Add the blotted pumpkin and whisk until evenly incorporated. The mixture should be smooth and thick rather than watery.

In a separate bowl, whisk together the flour, cinnamon, pumpkin pie spice, and salt.

Add the dry ingredients to the pumpkin mixture. Fold gently with a rubber spatula until no streaks of flour remain. Do not overmix. The batter will be thick and spreadable.

Transfer the batter to the prepared pan and spread it into an even layer, making sure it reaches the corners.

Stir together the granulated sugar and cinnamon for the topping. Sprinkle it evenly over the surface of the blondie batter.

Bake for 30 minutes, or until the edges are set and lightly golden and the center no longer appears wet. A toothpick inserted into the center should come out with a few moist crumbs, but not raw batter.

Place the pan on a wire rack and let the blondies cool completely in the pan. For the cleanest slices and chewiest texture, allow them to rest for at least 2 hours before cutting.

Use the parchment overhang to lift the blondies out of the pan. Cut into 16 squares.