Preheat your oven to 350 degrees f, and spray a 9x13 inch pan with non-stick spray. Set aside.

In a large mixing bowl, whisk together butter yellow cake mix, water, butter, and 3 eggs. Whisk until well combined and there are no lumps of cake mix.

Pour into the 9x13 inch pan, and smooth out evenly.

In another large mixing bowl, whisk together pumpkin puree, brown sugar, half and half, 3 eggs, pumpkin pie spice, and salt.

Pour the pumpkin mixture evenly over the cake mixture, and gently smooth out evenly.

Bake the cake in a 350 degree oven for 50-60 minutes, until a toothpick inserted in the middle of the cake layer comes out clean.

Allow the cake to cool, then prepare the frosting.

In a large mixing bowl, use a mixer to beat cream cheese until smooth.

Add in powdered sugar and vanilla, and mix to combine, until smooth.

In a separate bowl, use a mixer to mix the heavy whipping cream for 2-3 minutes, until peaks begin to form and it has a whipped cream consistency.

Add the whipped cream to the frosting mixture, and mix well to combine.

Smooth the frosting evenly over the top of the cake.

Enjoy! Refrigerate any leftovers.