In a medium bowl, whisk together the flour, baking powder, baking soda, pumpkin pie spice, and salt.
1 ¾ cups all-purpose flour, 1 tsp baking powder, ½ tsp baking soda, 1 tbsp pumpkin spice, ¼ tsp salt
In a separate large bowl, whisk together sugar, oil, eggs, pumpkin puree, and vanilla until smooth.
1 cup brown sugar, 1/4 cup granulated sugar, 2/3 cup vegetable oil, 2 large eggs, 1 cup pumpkin puree, 1 tsp vanilla extract
Pour the cake batter into the prepared pan and spread evenly. Sprinkle the streusel evenly on top of the batter.
Bake for 45-55 minutes, or until a toothpick inserted into the center comes out clean.