Start by preheating your oven to 350 degrees. Line a baking dish with parchment paper.
Then in a stand mixer cream your butter, sugar until light and creamy.
Add in your eggs, one at a time, pumpkin puree, and vanilla extract.
Then in a large bowl, add in your flour, pumpkin spire, baking powder, and salt, whisk and sit aside.
Then as you are slowly blending your mixture, work in your dry flour mix.
Pour batter into the pan, and bake for 20 minutes.
Remove from the oven and allow to cool on a cooling rack.
Once your pumpkin bars are cooled, start making your frosting.
Cream together butter, vanilla, and cream cheese until blended.
Add in your powdered sugar and cinnamon and mix until light and fluffy.
Spread frosting on cooled pumpkin bars, and then sprinkle with your sprinkles.