Preheat oven to 350˚. Lightly spray an 8-cup large muffin tin with cooking spray. In a large bowl, whisk together flour, salt, baking powder, cinnamon, and nutmeg. Add sweet potato and walnuts. Make a well in center of flour mixture.
In a medium bowl, whisk together sugars, eggs, and oil. Add sugar mixture to flour mixture, stirring just until moistened. Spoon batter into prepared muffin cups.
Bake until a wooden pick inserted in center comes out clean, 25 to 30 minutes. Let cool in pan for 5 minutes. Remove from pan. Spread Cream Cheese Frosting evenly on each mini cake. Garnish with walnuts, if desired.
Recipe by Southern Lady Magazine at https://southernladymagazine.com/sweet-potato-mini-cakes/