Preheat the oven to 350 F. and line an 8x8 baking dish with parchment paper.
In a medium bowl or stand mixer, combine all wet ingredients. Use an electric mixer to blend until smooth (about 1 minute).
Add all dry ingredients (except baking powder) and mix until well combined. Finally, fold in the baking powder until just combined.
Bake at 350 F. for 23-25 minutes or until a toothpick comes out with a few moist crumbs. Allow it to cool completely.
*Optional:* While the gluten-free pumpkin bars are cooling, make the maple cream cheese frosting by combining all ingredients in a medium bowl and beating on high with an electric mixer (ensure your cream cheese and butter are softened). If the glaze looks clumpy, microwave for 15 seconds, then continue mixing until smooth. The consistency may vary depending on the softness of your butter and cream cheese. For a thicker frosting, refrigerate for 20-30 minutes.
Once the gluten-free pumpkin bars are cooled, frost them with maple cream cheese frosting and sprinkle with cinnamon if desired. Enjoy! Store in an airtight container in the refrigerator for up to 5 days (if left unfrosted, you can store the bars at room temperature for up to 3 days).