Ingredient:

• 1 1/4 cups all-purpose flour 
• 1/4 cup unsweetened cocoa powder 
• One teaspoon baking powder
• One teaspoon baking soda
• 1/8 teaspoon salt
• 1/2 cup low-fat buttermilk
• 1/2 teaspoon vanilla
• 3/4 cup cooked, mashed, cooled sweet potato 
• 1/2 cup vegetable oil 
• 3/4 cup sugar
• Two eggs

Frosting: You can use a store bought frosting or you can make your own. See instructions below

• 2-Minute Frosting:
• Two Tablespoons butter softened
• One cup powdered sugar
• One tablespoon unsweetened cocoa powder 
• One teaspoon vanilla
• One tablespoon milk to soften

Method:

1. Preheat your oven to 350° Fahrenheit. Then line a 9-inch round cake pan with parchment paper.
3. Peel and dice the sweet potato. Boil or steam until soft. Then mash with a fork. And set aside to cool.
4. Sift dry ingredients into a bowl and Set aside.
5. Combine the buttermilk, vanilla, and the mashed sweet potato in a small bowl and set aside.
6. Use an electric mixer set to medium-high, beat the oil, sugar & eggs for 3-4 minutes until thickened.
7. At the lowest speed, add buttermilk mixture followed by the flour mixture.
8. Pour mixture into prepared pan. And bake cake for 30 minutes or until a toothpick inserted in the center comes out clean. Cool completely in the pan on a wire rack, then add frosting.
9. Frosting:
10. In a bowl with an electric hand mixer, beat butter, powdered sugar, cocoa, and vanilla.
11. Adjust consistency with milk, beating well.