Preheat your oven to 350°F (175°C). Line an 8x8 inch (20x20 cm) baking pan with parchment paper, leaving some overhang for easy removal of the bars.
In a large mixing bowl, combine the almond flour, granulated erythritol, pumpkin pie spice, baking powder, and salt. Whisk these dry ingredients together to remove any clumps and ensure even distribution of the spices and leavening agents.
In a separate bowl, mix together the pumpkin puree, melted butter, eggs, and vanilla extract until smooth. This is your wet mixture that will provide the moisture and structure to the bars.
Gradually add the wet ingredients to the dry ingredients, stirring until you have a uniform batter. Be careful not to overmix, as this can lead to denser bars.
Pour the batter into the prepared baking pan, using a spatula to spread it into an even layer.
Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs.
While the pumpkin bars are baking, prepare the cream cheese frosting by beating together the softened cream cheese, softened butter, powdered erythritol, and vanilla extract until smooth and creamy.
Once the pumpkin bars have finished baking, allow them to cool in the pan for about 10 minutes before lifting them out onto a wire rack to cool completely.
When the bars are completely cool, spread the cream cheese frosting evenly over the top. Cut into 12 bars.
Serve immediately or store in an airtight container in the refrigerator for up to 5 days.