Add butter, sugar, vanilla, eggs, cinnamon, pumpkin pie spice, pumpkin puree, sour cream and milk together and blend until smooth.
Add the salt, flour, baking powder and baking soda to the wet mixture and blend until the batter is smooth and well mixed.
Line the cookie sheet with parchment paper and spray with non-stick spray.
Pour batter onto pan.
Bake for ~25 minutes or until the cake is cooked through and a toothpick comes out clean.
Cool cake completely.
In another bowl, add butter, cream cheese, pumpkin pie spice, cinnamon, vanilla, powdered sugar, whipping cream and salt together and whisk until smooth and fluffy.
Spread over cooked cake or use a piping tip to pipe frosting on.