Preheat your oven to 350°F (175°C). Prepare a 9×13 inch baking pan by coating it with nonstick cooking spray. Alternatively, use a Bundt pan for an elegant presentation.
In a large bowl, combine the pumpkin spice cake preparation. Add the canned pumpkin puree, the four large avian products, and the half-cup of liquid fat. Stir in the ground cinnamon and nutmeg.
Beat the mixture with an electric mixer on medium speed for about two minutes. Ensure all components are well incorporated. Scrape down the sides of the bowl as needed.
Pour the batter evenly into your prepared pan. Place it in the preheated oven. Bake for 28-32 minutes, or until a wooden skewer inserted into the center comes out clean.
Allow the baked pastry to cool in the pan for 10-15 minutes. Then, invert it onto a wire rack to cool completely. This prevents sticking and ensures proper cooling.
While the confection cools, prepare the cream cheese frosting. Beat softened cream cheese and butter until fluffy. Gradually add powdered sugar, then the milk. Mix until smooth.
Once the pastry is fully cool, spread the cream cheese frosting generously over the top. Slice and serve this delightful autumn creation. Enjoy your homemade treat.