Make the Blondie

1. Preheat the oven to 350°F (176°C) and spray a 9×9 pan with non-stick baking spray. Line it with parchment paper, letting it hang over two sides to easily lift the bars out later. Set aside.
2. In a small bowl, combine the flour, baking powder, and salt. Set aside.
3. In a large bowl, whisk together the melted butter and brown sugar. Add the vanilla extract and egg, whisking until well combined.
4. Add the dry ingredients to the wet ingredients and mix until just combined.
5. Spread the batter evenly into the prepared pan. Bake for 10-15 minutes (I baked it for 12 minutes) or until a toothpick inserted comes out clean. The blondie should puff up and appear matte on top.

For the Pumpkin Pie Filling

1. While the blondie bakes, whisk together the pumpkin puree, eggs, and light brown sugar in a large bowl.
2. Add the remaining ingredients and whisk until well combined.
3. Pour the pumpkin filling over the hot blondie (you don’t need to remove it from the oven). Spread the filling evenly as you pour to avoid pooling in one spot.
4. Return the pan to the oven and bake for 25-30 minutes, or until the filling begins to set and looks firm enough to support the streusel topping. It should no longer look sloshy.

Make the Streusel

1. In a medium-sized bowl, combine the flour, sugar, cinnamon, and salt.
2. Add the vanilla and melted butter, stirring until evenly distributed and crumbly.
3. Once the pumpkin filling is ready, sprinkle the streusel evenly over the top.
4. Bake for another 5-10 minutes, until the topping looks less glossy and the center has risen and set.

Cool & Serve

1. Remove from the oven and allow the blondies to cool at room temperature for 1 hour.
2. Transfer to the refrigerator to cool completely, about 2-3 hours.
3. Slice into bars and serve. Store leftovers in an airtight container. Best if eaten within 4-5 days.