Preheat oven to 350.
Generously grease a 10" bundt pan. Set aside.
In a medium bowl, combine the flour, baking soda, salt and pumpkin spice. Whisk to blend and set aside.
In a large bowl, combine the pumpkin, sugar, brown sugar, oil, eggs, and vanilla.
Whisk until combined.
Add the dry ingredients to the wet ingredients and whisk until blended.Set aside.
Using a hand mixer, beat 12 ounces of cream cheese for filling until fluffy.
Add remaining filling ingredients and beat until blended.
Spread half of the cake batter into the prepared pan.
Spread all of the filling on top of cake batter.
Spread remaining cake batter on top of filling.
Bake for about an hour until a toothpick inserted into the cake comes out clean.
Allow to cool in the pan for an hour inside the pan.
Invert and turn out onto serving plate.
Use hand mixer to beat cream cheese and butter for topping until fluffy.
Beat in powdered sugar. until incorporated.
Gradually add just enough milk to make topping just pourable.
Drizzle toping over cake.