Preheat the oven to 350 degrees, line cupcake pan with cupcake liners.
In a medium bowl, whisk the flour, baking powder, baking soda, cinnamon, nutmeg and salt. Set Aside
In another bowl, add the sweet potatoes, milk, vegetable oil, and vanilla. Set Aside.
In the bowl of your mixer, add the butter and mix at medium speed until smooth. Gradually add the sugar and continue to mix on medium speed for 3 to 5 minutes until lightened in color and fluffy.
Add the eggs one at a time, mixing after each until the yellow of the yolk is blended.
With the mixer on low speed, alternately add the flour mixture and milk mixture, beginning and ending with the dry ingredients (3 additions of dry ingredients and 2 of the milk/sweet potato mixture). After the last addition, mix just until combined.
This recipe makes about 7 cups of batter. Fill the cupcake liners with about ¼ cup of batter each (for a total of about 28 cupcakes.)
Bake at 350 degrees for 18-20 minutes (Peek in at the 15 minute mark and adjust time as needed.) Bake until a toothpick inserted in the center comes out clean or with just a few crumbs attached, or when tops spring back when lightly touched. Let cool 5 to 10 minutes and turn out.