Preheat oven to 350°F (175°C). Grease and flour a 10-inch bundt pan.
In a large bowl, cream together butter and sugar until light and fluffy.
Add eggs one at a time, beating well after each addition.
Mix in mashed sweet potatoes.
In another bowl, whisk together flour, baking powder, baking soda, salt, cinnamon, nutmeg, and ginger.
Gradually add dry ingredients to the wet mixture, alternating with milk, beginning and ending with dry ingredients.
Stir in vanilla extract.
Pour batter into prepared pan.
Bake for 1 hour or until a toothpick inserted into the center comes out clean.
Cool in pan for 10 minutes, then turn out onto a wire rack to cool completely.