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slice of sweet potato cake with marshmallow frosting square image.
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Sweet Potato Layer Cake
Prep Time
1 hr
Cook Time
25 mins
 
Layers of moist, gently spiced sweet potato cake are surrounded by swirls of marshmallow frosting for a mouthwatering masterpiece that tastes as epic as it looks.
Course: Dessert
Cuisine: American
Keyword: marshmallow frosting, sweet potato cake, thanksgiving cake
Servings: 12 servings
Author: Jackie
Ingredients
Cake Layers
  • 2 cups sweet potato puree from 2 large sweet potatoes
  • 2 ½ cups all purpose flour
  • 1 ½ teaspoons baking soda
  • 1 ½ teaspoons baking powder
  • 1 teaspoon salt
  • 1 tablespoon cinnamon
  • ½ teaspoon all-spice
  • ½ teaspoon ground nutmeg
  • ½ teaspoon cardamom
  • ½ cup butter softened
  • ½ cup vegetable oil
  • 4 large eggs
  • 1 ¾ cup sugar
  • 2 teaspoons vanilla
  • ½ cup buttermilk
  • ½ cup walnuts pecans, or candied pecans
Marshmallow Frosting
  • ¾ cup sugar
  • ⅔ cup light corn syrup
  • 4 large egg whites
  • ½ teaspoon cream of tartar
  • ¼ teaspoon salt
  • 1 ½ teaspoons vanilla extract
Instructions
  1. To make the sweet potato puree, preheat oven to 425º. On a baking sheet lined with aluminum foil, prick sweet potatoes all over with a fork. Bake until tender, 45 to 50 minutes.Let cool, remove the skin and smash with a fork or blend until smooth.
  2. To make the cake layers, preheat oven to 350 degrees. Grease and flour three 8-inch round cake pans.
  3. In a medium sized bowl, whisk together flour, baking soda and baking powder, salt, and spices; set aside.
  4. In a large bowl, beat together butter, oil, and sugar until light and fluffy.
  5. Add eggs, one at a time, beating thoroughly and scraping down the sides of the bowl before adding the next egg.
  6. Whisk in the sweet potato puree and vanilla.
  7. Add half of the flour mixture to the batter and mix until combined. Add the buttermilk to the batter and mix until combined. Finally, add the remaining flour mixture and mix until well combined and smooth. Scrape down the sides of the bowl as needed to ensure everything is well combined. This batter will be thick.
  8. Divide the batter evenly between the prepared cake pans.
  9. Bake for 20-25 minutes, or until a toothpick inserted in the middle comes out with a few crumbs.
  10. Remove cakes from the oven and allow to cool for 3-4 minutes, then remove cake layers from pans to a cooling rack to finish cooling.
  11. To make the Marshmallow Frosting, bring a small pot with 3-4 inches of water to a boil.
  12. In a large heatproof bowl (I use the metal bowl of my mixer), add all frosting ingredients. Place the bowl over the boiling water and whisk until sugar has dissolved and the mixture feels smooth and no longer grainy- about 3 minutes.
  13. Remove bowl from heat and beat the mixture on high speed until it has doubled in size, white, and is no longer warm- about 5 minutes.
  14. To assemble the cake Place the first cake layer on a serving plate or cardboard cake circle.Spread about a cup of marshmallow frosting into an even layer on top of the cake.
  15. Top the frosting with the second layer of cake, then repeat another layer of frosting.
  16. Top the cake with the final layer of cake, then frost the outside of the cake.
  17. If possible, refrigerate the cake for 1 hour.
  18. Right before serving, toast the outside of the cake with a kitchen torch. Garnish the top rim of the cake with nuts.
  19. Serve and enjoy!
Recipe Notes

Tips-

You can use canned sweet potato puree in lieu of fresh sweet potatoes.

Make the puree and cake layers in advance.

Frosting is best made the same day as assembling the cake.

To get a golden brown finish, on the marshmallow frosting, use the blowtorch close to the cake and quickly to avoid burning.

Garnish cake with walnuts, pecans, or candied pecans.