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Sweet Potato Chocolate Cake

Sweet potato chocolate cake with moist dark layers and a glossy chocolate ganache frosting. The recipe bakes in two 9-inch rounds, then frosts with a rich ganache base and fluffy powdered-sugar finish.
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Prep Time 30 minutes
Cook Time 40 minutes
Total Time 1 hour 10 minutes
Servings: 12 servings
Course: Dessert
Cuisine: American
Ingredients Equipment Method Notes

Ingredients
  

For cake
  • 2 cup flour
  • 1 cup cocoa powder
  • 2 tsp baking powder
  • 1 tsp baking soda
  • 1 tsp cinnamon
  • 0.5 tsp salt
  • 1 cup butter
  • 2 cup sugar
  • 4 eggs
  • 1 cup sweet potato puree
  • 1 cup buttermilk
  • 2 tsp vanilla
For chocolate ganache frosting
  • 16 oz dark chocolate chips
  • 1 cup heavy cream
  • 4 tbsp unsalted butter
  • 2 cup powdered sugar
  • 1 tsp vanilla

Equipment

  • 1 sheet pan
  • 1 stand mixer

Method
 

Bake the cake layers
  1. Preheat oven to 350F and grease two 9-inch round pans. Set them aside so the batter can go in immediately.
  2. Beat butter and sugar until light and creamy. Keep beating to fully dissolve the sugar for a smooth crumb.
  3. Add eggs one at a time, then beat in sweet potato puree, buttermilk, and vanilla. Mix just until the batter looks uniform.
  4. Fold in flour, cocoa powder, baking powder, baking soda, cinnamon, and salt until no dry streaks remain. The batter should be thick and glossy with a dark color.
  5. Divide the batter between the two pans and smooth the tops. Aim for even layers so the cake bakes flat.
  6. Bake for 35-40 minutes at 350F until a toothpick in the center comes out clean or with a few moist crumbs. Remove and cool completely before frosting.
Make and spread the chocolate ganache frosting
  1. Heat heavy cream until steaming, then pour over dark chocolate chips and unsalted butter. Make sure all chocolate is submerged for an even melt.
  2. Rest the mixture for 2 minutes, then stir until smooth. The ganache should look shiny and dark with no lumps.
  3. Cool the ganache until spreadable, about room temperature, then beat with powdered sugar and vanilla until fluffy. Stop when it holds soft peaks and is thick enough to frost.
  4. Frost between layers and then all over the cake. Use a spatula to drag frosting down the sides for a clean, even finish.

Notes

Pro tip: cool the cake completely before frosting; warm layers can melt ganache and cause sliding. Store covered in the refrigerator up to 4 days (freeze frosted cake up to 2 months, thaw overnight in the fridge). For a lower-sugar option, reduce powdered sugar to 1.5 cups and add 2-3 tbsp extra cocoa or a small splash more vanilla to keep the frosting flavorful.