Sweetapolita’s Autumn Delight Cake


Oct 20

Sweet potato cake layers with toasted marshmallow filling, brown sugar frosting and candied pecans.

First thing’s first: I love sweet potatoes! I probably have one almost every day. (Seriously. Fresh out of the oven with brown sugar and almond butter, diced and roasted with olive oil, salt and a little cinnamon, or in french fry form. Hmmm. So good.) One of my favorite sweet potato dishes is my mom’s Thanksgiving sweet potato casserole with toasted marshmallows. I’m sure many of you serve a similar dish at your Thanksgiving Day feast, and if it’s your favorite part of the meal, as it is mine, you’re going to swoon over this cake.


Sweetapolita created this beauty, and it’s one of my absolute favorite cakes of all time. Yup, add it to the list with the chocolate salted caramel and gingerbread latte. To me, it’s my mom’s sweet potato casserole in cake form: nearly two pounds of mashed sweet potatoes, lots of cinnamon, toasted marshmallows and candied pecans! Oh, and then there’s the addition of crystallized ginger and brown sugar buttercream! So many flavors and textures – it’s pure heaven. 

I actually made this cake for a wedding, so I couldn’t slice into it to show you just how dreamy it looks inside. Check out the original post here for pictures of the cake layers. If you’re not already convinced you need to make this cake, Rosie’s pictures are sure to convince you.

Enjoy!

Sweetapolita's Autumn Delight Cake

Yield One 4-layer, 8-inch cake

Sweet potato cake layers with toasted marshmallow filling, brown sugar frosting and candied pecans.

Ingredients

For the Sweet Potato Cake

  • 3 large sweet potatoes (about 900 g)
  • 2 cups (400 g) sugar
  • 4 large eggs, at room temperature
  • 1 1/4 cups (315 ml) sunflower oil (or vegetable, safflower, canola oil)
  • 2 cups (230 g) cake flour
  • 1 tablespoon (7 g) ground cinnamon
  • 2 teaspoons (8 g) baking powder
  • 1 teaspoon (7 g) salt
  • 1 teaspoon (3 g) nutmeg
  • 1/2 teaspoon (1.5 g) ground ginger
  • 2 tablespoons (30 ml) brandy or dark rum (optional - I didn't use it, but you could also use a imitation flavor)
  • 2 teaspoons (10 ml) pure vanilla extract
  • 3/4 cup (120 g) crystallized ginger, chopped

For the Toasted Marshmallow Filling

  • 16 large white marshmallows
  • 1 1/2 cup (125 g) confectioners' sugar, sifted
  • 1 cup (227 g / 2 sticks) unsalted butter, at room temperature
  • 1/2 teaspoon (2.5 ml) pure vanilla extract
  • 1 jar (about 200 g) marshmallow cream/fluff

For the Brown Sugar Frosting

  • 5 large egg whites (150 g)
  • 1 1/4 cups (250 g) light brown sugar
  • 1 1/2 cups (340 g/ 3 sticks) unsalted butter, softened and cut into cubes
  • 2 teaspoons (10 ml) pure vanilla extract
  • pinch of salt
  • a few pinches of cinnamon, to taste

UPDATE

I've had some issues with the meringue brown sugar frosting, and have heard some of you have too. So, as an alternative to the meringue buttercream in the original recipe, here's a cinnamon sugar buttercream I've come up with that I have started using with this cake.

Cinnamon Sugar Buttercream (alternative to the frosting above)

  • 1 1/2 cups (3 sticks) unsalted butter, room temperature
  • 5 cups powdered sugar, sifted
  • 1/2 cup light brown sugar
  • 2 teaspoons pure vanilla extract
  • 1 1/2 teaspoons cinnamon
  • pinch of salt

For the Candied Pecans

  • 2 tablespoons (28 g) unsalted butter
  • 2 tablespoons (24 g) brown sugar
  • 1 cup (100g) pecan pieces

Instructions

For the Sweet Potato Cake

  1. Preheat oven 350 degrees F. Grease two 8-inch round cake pans, dust with flour, tap out excess and set aside.
  2. Place the sweet potatoes on a microwave safe plate and pierce them with a fork. Microwave until they are tender (about 7-8 minutes each side). Carefully, remove the skin when cool enough to touch and mash the flesh into a coarse puree.
  3. In the bowl of an electric mixer fitted with a paddle attachment, beat the sugar and eggs together on medium-high speed until light and fluffy, about five minutes. Add the oil and beat on medium until combined. Add the cooled sweet potato puree and mix until combined.
  4. Sift dry ingredients together (cake flour, cinnamon, baking powder, salt, nutmeg, and ground ginger) and then add to sweet potato mixture.
  5. Mix in brand/dark rum (if using) and vanilla. Gently stir in crystallized ginger.
  6. Evenly distribute batter into the prepared pans (weigh them if possible with digital kitchen scale), smooth with a small offset palette knife and place in the center of the middle rack of the oven, about two inches apart. Bake until a knife or skewer inserted into the center comes out clean, about 40 minutes (mine took 45 minutes).
  7. Let pans cool on wire rack 10 minutes, invert cakes onto rack and cool them completely.

For the Toasted Marshmallow Filling

  1. Place marshmallows on cookie sheet lined with parchment paper and sprayed with nonstick cooking spray. Place on lower rack of oven, and broil marshmallows until nice and brown on top, about 30-60 seconds. Remove pan from oven and gently turn the marshmallows over, and broil until they are golden brown. (Be sure to keep an eye on them, they burn quickly).
  2. In an electric mixer fitted with paddle attachment, combine butter and icing sugar on low until blended, about one minute. Add vanilla and mix on medium-high speed for about three minutes.
  3. Add marshmallow cream and (cooled) toasted marshmallows, and mix on lowest setting for about one minute.

For the Brown Sugar Frosting (Sweetapolita's Swiss Meringue Buttercream)

  1. Wipe the bowl of an electric mixer with a paper towel and lemon juice, to remove any trace of grease. Add egg whites and sugar, and simmer over a pot of water (not boiling), whisking constantly but gently, until temperature reaches 160 degrees F, or if you don't have a candy thermometer, until the sugar has completely dissolved and the egg whites are hot.
  2. With the whisk attachment of mixer, begin to whip until the meringue is thick, glossy, and the bottom of the bowl feels neutral to the touch (this can take up to 10 minutes or so). Don't begin to add the butter until the bottom of the bowl feels neutral, not warm at all.
  3. Switch over to the paddle attachment and, with the mixer on low speed, add butter cubes, one at a time, until incorporated, and mix until it has reached a silky smooth texture (if it curdles, keep mixing and it will come back.) If mixture is too runny, refrigerate for 15-30 minutes and continue mixing with paddle attachment until it comes together. Add vanilla and salt, continuing to beat on low speed until well combined. Add cinnamon to taste and blend.

For the Cinnamon Sugar Buttercream (for my traditional buttercream)

  1. In a stand mixer fitted with the paddle attachment, beat the butter on medium speed for 30 seconds. 
  2. With the mixer on low, add the powdered sugar, one cup at a time, until it's all incorporated. Turn the mixer on medium and beat for about a minute.
  3. Add the remaining ingredients and beat for another 5 minutes, until light and fluffy. 
  4. Use a wooden spoon to mix by hand for a couple minutes to push out any air pockets before frosting your cake.

For the Candied Pecans

  1. Melt the butter in small pan. Mix in brown sugar, and add the pecans. Toss to coat.
  2. Cook on medium low heat for about 15 minutes, stirring occasionally. Be sure to watch carefully so they don't burn.
  3. Turn out onto parchment paper or aluminum foil and let cool for five minutes, break apart into smaller pieces if using halves.

Assembly

  1. Slice both cake layers in half horizontally, so you have four cake layers. 
  2. Place the first layer on a place, pedestal or cake board cut side up (s0 bottom of the cake layer is touching the plate), and spread about 3/4 cup of the toasted marshmallow filling with a small offset palette knife, leaving 1" or so around the edge. Sprinkle with a handful of candied pecan pieces.
  3. Repeat previous steps until you get to the final cake layer. Place last layer face cake down and coat with a thin layer of frosting to lock in the crumbs. Chill the crumb coat for 10 minutes in the freezer.
  4. Frost cake with buttercream and top with a generous handful of candied pecans and crystallized ginger.
  5. Finished cake can be kept at room temperature for up to eight hours. Keep refrigerated in an airtight container if longer than 8 hours, but always serve at room temperature (Swiss Buttercream should never be served cold, as it goes back to a cold butter texture).

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