• Preheat the oven to 350 degrees and line an 8x8-inch pan with parchment paper, allowing a little to hand over the sides. Then spray with non-stick spray. Set aside.

Shortbread Crust

• In a medium-sized bowl, mix together the flour, melted butter, powdered sugar, and cinnamon. Press the dough into the prepared baking pan and bake for 16-20 minutes, just until the outside starts to turn light brown.

Pumpkin Filling

• In a medium bowl, whisk together the flour, baking powder, pumpkin pie spice, and salt. Set aside.
• In an electric stand mixer using the whisk attachment, beat the eggs on medium speed until frothy (about 1 minute). Then beat in the sugar for 2 minutes.
• Add the oil and pumpkin puree and mix on medium speed until fully combined. Remove the bowl from the stand mixer and pour in the dry ingredients. Use a rubber spatula to fold all of the ingredients. Be careful not to overmix.
• Pour the filling over the warm shortbread crust and set it aside as you make the streusel topping.

Streusel Topping

• In a medium bowl, mix together the oats, brown sugar, flour, pumpkin pie spice, and salt using a spoon. Then mix in the melted butter until everything is fully coated. Sprinkle the topping evenly over the filling.
• Bake the bars for 35-40 minutes, or until the center is set. Use a toothpick to check the center for doneness. Cool for at least 1 hour before serving and adding the glaze.

Glaze (optional)

• In a small bowl, mix together the powdered sugar, milk, and vanilla extract. Drizzle over the cooled bars.
• Keep any leftover pumpkin bars in an airtight container at room temperature for 2 days or in the refrigerator for up to 5 days.