Preheat the oven to 350°F. Grease and lightly flour a 9×13-inch baking pan or line it with parchment paper for easier removal.

Mix the Dry Ingredients. In a large mixing bowl, combine together the flour, baking powder, cinnamon, cloves, ginger, nutmeg, and salt. Set aside.

Mix the Wet Ingredients. In a separate large bowl, using an electric mixer or stand mixer fitted with a whisk attachment, beat the eggs at medium speed until slightly foamy, about 2 minutes. Gradually add the packed brown sugar, continuing to beat until the mixture is thick and smooth, approximately 2 minutes.

With the mixer running on low speed, slowly add the vegetable oil, followed by the pumpkin puree and vanilla extract. Beat until well combined, scraping down the sides of the bowl as needed.

Combine the Mixtures. Gradually fold the dry ingredients into wet ingredients using a spatula or wooden spoon. Mix until combined—avoid overmixing to keep the bars light and tender.

Bake the Bars. Pour the batter into the prepared baking pan, spreading it evenly. Bake in the preheated oven for 20-25 minutes, or until a toothpick inserted into the center comes out clean. Allow the bars to cool completely in the pan on a wire rack.

Prepare the Frosting. While the bars are cooling, prepare the frosting. In a medium bowl, using an electric mixer, beat the softened cream cheese on medium speed until smooth. Gradually add the powdered sugar and vanilla extract, beating until creamy and well incorporated.

Frost the Bars. Once the bars have cooled completely, spread the cream cheese frosting evenly over the top using a spatula or the back of a spoon. For clean cuts, refrigerate the bars for 30 minutes before slicing.

Serve. Slice the frosted pumpkin bars into squares and serve. These bars are best enjoyed chilled or at room temperature. Store any leftovers in an airtight container in the refrigerator for up to 4 days.