In a large bowl, sift together the flour, baking soda, baking powder, and salt.
In a separate large bowl, use a mixer or stand mixer to cream the softened butter and cream cheese for roughly 3 minutes.
Add the sugars and mix for 10 minutes.
Add the smoothly blended sweet potatoes and mix to combine.
Add one egg at a time, combining each egg before adding the next.
Alternate adding the milk and flour mixture. Start and end with the flour.
You can add the spices during the first addition of the flour and the vanilla during the first addition of the milk.
Pour the batter into your prepared pound cake pan.
Bake at 325°F for 1 hour 20 minutes, or until the cake is done.
Allow the cake to cool before removing it from the pan.