Ingredients

For the Sweet Potato Cake:

  • 2 cups (400g) granulated sugar
  • 1 cup (240ml) vegetable oil
  • 3 large eggs, room temperature
  • 2 cups (480g) mashed sweet potatoes (about 2 medium sweet potatoes, baked and mashed)
  • 1 tablespoon vanilla extract
  • 2 ½ cups (315g) all-purpose flour
  • 2 teaspoons baking powder
  • 1 teaspoon baking soda
  • ½ teaspoon salt
  • 2 teaspoons ground cinnamon
  • ½ teaspoon ground nutmeg
  • ¼ teaspoon ground ginger
  • ½ cup (120ml) buttermilk, room temperature

For the Cream Cheese Frosting:

  • 8 oz (225g) cream cheese, softened
  • ½ cup (115g) unsalted butter, softened
  • 4 cups (480g) powdered sugar, sifted
  • 1 teaspoon vanilla extract
  • 1-2 tablespoons heavy cream (as needed for consistency)

For the Toasted Marshmallow Meringue:

  • 4 large egg whites
  • 1 cup (200g) granulated sugar
  • ¼ teaspoon cream of tartar
  • 1 teaspoon vanilla extract

Equipment

  • Three 8-inch round cake pans
  • Parchment paper
  • Mixing bowls
  • Electric mixer (stand or hand)
  • Whisk
  • Spatula
  • Cooling racks
  • Double boiler or heatproof bowl
  • Kitchen torch or oven broiler

Instructions

Prepare the Sweet Potato Cake:

  1. Preheat Oven: Preheat your oven to 350°F (175°C). Grease three 8-inch round cake pans, line the bottoms with parchment paper, and lightly flour the sides.
  2. Mix Wet Ingredients: In a large mixing bowl, beat the granulated sugar and vegetable oil together until combined. Add the eggs one at a time, beating well after each addition. Mix in the mashed sweet potatoes and vanilla extract until smooth.
  3. Combine Dry Ingredients: In a separate bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, nutmeg, and ginger.
  4. Combine Wet and Dry: Gradually add the dry ingredients to the wet ingredients in three additions, alternating with the buttermilk, starting and ending with the dry ingredients. Mix until just combined; do not overmix.
  5. Bake: Divide the batter evenly among the prepared pans. Smooth the tops with a spatula. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
  6. Cool: Allow the cakes to cool in the pans for 10 minutes, then transfer to wire racks to cool completely.

Prepare the Cream Cheese Frosting:

  1. Beat Cream Cheese and Butter: In a large bowl, use an electric mixer to beat the softened cream cheese and butter until smooth and creamy, about 2 minutes.
  2. Add Sugar and Vanilla: Gradually add the powdered sugar, 1 cup at a time, beating on low speed until incorporated. Add the vanilla extract and beat on medium speed until light and fluffy, about 2-3 minutes.
  3. Adjust Consistency: If the frosting is too thick, add heavy cream 1 tablespoon at a time until you reach a spreadable consistency. Set aside.

Assemble the Cake:

  1. Level Cakes: Once the cakes are completely cool, use a serrated knife to level the tops if needed for even stacking.
  2. Layer and Frost: Place one cake layer on a serving plate or cake stand. Spread about ¾ cup of cream cheese frosting evenly over the top. Add the second cake layer and repeat with another ¾ cup of frosting. Place the third cake layer on top.
  3. Frost Exterior: Apply a thin layer of frosting (crumb coat) over the top and sides of the cake to trap crumbs. Refrigerate for 15 minutes to set. Then, apply a final, thicker layer of frosting over the entire cake, smoothing it with a spatula or creating decorative swirls.

Prepare the Toasted Marshmallow Meringue:

  1. Set Up Double Boiler: Fill a saucepan with 1-2 inches of water and bring to a simmer. Place a heatproof bowl over the saucepan, ensuring the bottom doesn’t touch the water.
  2. Heat Egg Whites and Sugar: In the bowl, combine the egg whites, granulated sugar, and cream of tartar. Whisk constantly over the simmering water until the mixture reaches 160°F (71°C) on a candy thermometer or until the sugar is fully dissolved (rub a small amount between your fingers to check; it should feel smooth).
  3. Whip Meringue: Remove the bowl from heat. Using an electric mixer, beat the mixture on high speed until stiff, glossy peaks form, about 5-7 minutes. Add the vanilla extract and beat for another 30 seconds.
  4. Decorate: Spread or pipe the meringue over the top of the frosted cake, creating peaks and swirls with a spatula or the back of a spoon.

Toast the Meringue:

  1. Using a Kitchen Torch: Carefully use a kitchen torch to toast the meringue, moving the flame in small circles until the peaks are golden brown.
  2. Using an Oven Broiler (Alternative): If you don’t have a torch, preheat your oven broiler to high. Place the cake on a baking sheet and broil for 30-60 seconds, watching closely to avoid burning, until the meringue is toasted.

Serve:

  1. Slice and Serve: Let the cake sit at room temperature for 10-15 minutes before slicing to allow the frosting to soften slightly. Use a sharp knife, wiping it clean between cuts for neat slices.
  2. Storage: Store leftovers in an airtight container in the refrigerator for up to 3 days. Bring to room temperature before serving for the best texture.

Tips:

  • Sweet Potatoes: Bake sweet potatoes at 400°F (200°C) for 45-60 minutes until soft, then scoop out the flesh and mash until smooth. Canned sweet potato puree can be used in a pinch.
  • Meringue Safety: Heating the egg whites to 160°F ensures they are safe to eat. Work quickly to toast the meringue to maintain its structure.
  • Make Ahead: Bake the cake layers a day in advance and wrap tightly in plastic wrap once cooled. The frosting can also be made ahead and refrigerated; re-whip before using.

Yield:

  • Serves: 12-16
  • Prep Time: 45 minutes
  • Cook Time: 30 minutes
  • Total Time: About 2 hours (including cooling)

Enjoy this indulgent Toasted Marshmallow Sweet Potato Cake, perfect for fall gatherings or any special occasion!