Preheat the oven to 375 degrees F (190 degrees C).
To make the browned butter, heat the Butter (1 1/2 cup) in a saucepan over medium heat until it starts to foam, smells nutty, and the milk solids start to turn golden brown.
Once it’s cooled slightly, pour it into a measuring cup. You will need 1 cup of the browned butter, which will have rendered down while cooking. Depending on the type of butter you use, you might have slightly more than 1 cup after browning.
In a large bowl or standing mixer, cream the Egg (4), Unsweetened Pumpkin Purée (1 can), and 1 cup of browned butter together just until smooth.
Sift the All-Purpose Flour (2 cup), Granulated Sugar (1 1/2 cup), Baking Powder (1 1/2 teaspoon), Baking Soda (1 teaspoon), Ground Cinnamon (2 teaspoon), Ground Ginger (1 teaspoon), Ground Cloves (1/2 teaspoon), Ground Nutmeg (1/2 teaspoon), and Salt (1/4 teaspoon) into the bowl and mix until well combined.
Pour batter into a well-greased 9×13-inch baking pan and smooth out the batter. Place into the preheated oven for 25-30 minutes or until the bars no longer jiggle in the middle.
In a standing mixer or hand mixer, cream the Cream Cheese (8 ounce) and Butter (1/2 cup) together until smooth. Add in the Powdered Confectioners Sugar (3 cup) and Cream (1 tablespoon) and whip on medium/high until the frosting becomes light and fluffy, about 2 minutes.
Once the bars have cooled completely, smooth the frosting on top. Feel free to sprinkle with cinnamon and sugar, sprinkles, or anything you might find festive. Slice to serve.