Sweet Potato Cake with Toasted Marshmallow Filling, Candied Pecans, and Brown Sugar & Cinnamon Swiss Meringue Buttercream

Sweetapolita has so many beautiful cakes, you really should see her pictures. She calls this Autumn Delight Cake, and it really is. I was going to save this recipe for the fall but I knew this one would make Maryam happy. This is her second celebratory cake. She landed her first job, only two days after her interview. I figured sweet potato cake would make this soon-to-be dietitian jump for joy. 

The recipe calls for 3 large sweet potatoes, weighing 900 grams total. I went ahead and weighed my potatoes to find I only needed two large sweet potatoes. If you don't have a scale to weight them, my first potato was 8 inches long x 2 inches wide and the other was 7 inches long x 3 inches wide. Good thing Maryam was around to help cook those sweet potatoes in the microwave. I'll write all the adaptions in the recipe below.

I was excited for the toasted marshmallow filling. It was my favorite component of the cake.

At first I was disappointed that the toasted marshmallows hinder the creaminess of the filling, but don't worry. You don't even notice the little brown bits when you eat it with cake.

The recipe says to cook the pecans for 15 minutes. That is ridiculous. After 4 minutes (on low heat!) I nearly burnt my pecans. Cook them on low just until the sugar dissolves, literally 2-3 minutes and remove from the pan. Nuts cook quickly when heated, and they taste much better when they aren't too browned.

After my cake was stacked, I put it in the freezer for 15-20 minutes. It's easier to frost because the cake is alittle firmer and the crumbs don't get everywhere. 

I appreciate how the buttercream recipe made plenty to frost the sides and bottom. Plenty. To the point that I put too much.

The recipe calls for alot of crystalized ginger in the cake, and I know that stuff is strong. So I decided not to add it and just used a tad bit more ground ginger. The spices in the cake all came out great.

Overall, I would make this cake again, except I was not expecting it to be so sweet. Even though it was delicious, I have to recommend to half the marshmallow filling. I love the beautiful white stripe which makes the cake stand out, but it just came out too sweet! 

Also, I would half the amount of nuts. I think less is more. It's more delightful to get a nut every now and then, rather than with each bite.

Lastly, the buttercream. TOO. MUCH. BUTTER. I adore swiss meringue buttercream and I loved the brown sugar flavor of this one, but that third stick of butter just ruined it. I should have known. Its been a while since I made it. I'm thinking half the amount of butter and it would have been great.

Sweet Potato Cake with Toasted Marshmallow Filling, Candied Pecans, and Brown Sugar & Cinnamon Buttercream

Adapted from Sweetapolita

Sweet Potato Cake

2 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) ground nutmeg

1 teaspoon (3 g) ground ginger

1 tablespoon (15 ml) rum extract

2 teaspoons (10 ml) pure vanilla extract

Directions

Preheat oven to 350 F. Grease two 8-inch round cake pans, dust with flour, tap out excess and set aside.

Peel and dice the sweet potatoes into cubes and place in a microwave-safe bowl and cover. Microwave until they are tender (about 8-10 minutes). Mash with a fork into a coarse puree.

In the bowl of an electric mixer fitted with the paddle attachment, combine the dry ingredients together (cake flour, cinnamon, baking powder, salt, nutmeg and ground ginger) and mix until blended. Transfer to another bowl and set aside. 

Beat the sugar and eggs together on medium-high speed until light and fluffy, about 5 minutes. Add the oil and beat on medium until combined. Add the cooled sweet potato puree and mix until combined. Slowly add dry ingredients. Mix in rum extract and vanilla. 

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 2 inches apart. Bake until a knife or skewer inserted into the center comes out clean, about 40 minutes.

Let pans cool on a wire rack 10 minutes. Invert cakes onto rack and cool them completely.

Candied Pecans

2 tablespoons (28 g) unsalted butter

2 tablespoons (24 g) brown sugar

1 cup (100 g) pecan pieces

Directions

Melt the butter in a small pan. Mix in brown sugar, and add the pecans. Toss to coat.

Cook on low heat for about 2-3 minutes, stirring occasionally. Be sure to watch carefully so they don’t burn. Do not brown nuts, remove from heat as soon as sugar looks dissolved. Turn out onto parchment paper or aluminum foil and let cool for 5 minutes; break apart into smaller pieces.

Toasted Marshmallow Filling

16 large white marshmallows

1 cup (125 g) icing sugar (confectioners' or powdered), sifted

1 cup butter (227 g)(2 sticks), at room temperature

1/2 teaspoon (2.5 mL) pure vanilla extract

1 jar (213 g) marshmallow cream (such as Marshmallow Fluff)

Directions

Turn on oven broiler and allow to come to full heat. Make sure the oven rack is placed at the top shelf, near the top heating element. Place marshmallows on cookie sheet lined with parchment paper. Place on top rack of oven, and broil marshmallows until nice and brown on top, about 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 very quickly.)

In an electric mixer fitted with paddle attachment, combine butter and icing sugar on low until blended, about 1 minute. Add vanilla and mix on med-high for about 3 minutes. Add marshmallow cream and toasted marshmallows, and mix on lowest setting for about 1 minute.

Brown Sugar & Cinnamon Swiss Meringue Buttercream

5 large egg whites (150 g)

1-1/4 cups (250 g) light brown sugar

3/4 cups (1.5 sticks)(170 g) unsalted butter, softened and cut into cubes

2 teaspoons (10 ml) pure vanilla extract

pinch of salt

a few pinches of cinnamon, to taste

Directions

Clean the bowl of your electric mixer very well, with plenty of soap suds, to be sure to remove any trace of grease. When clean and dry, add egg whites and sugar, and simmer over a pot of water (not boiling), whisking constantly but gently, until temperature reaches 160°F, or if you don't have a candy thermometer, until the sugar has completely dissolved and the egg whites are hot.

With 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 5-10 minutes). Don't begin adding butter until the bottom of the bowl feels neutral, and not warm.

Switch over to paddle attachment and, with mixer on low speed, add softened butter cubes, one at a time, until incorporated, and mix until it has reached a silky smooth texture (if curdles, keep mixing and it will come back to smooth). If mixture is too runny, refrigerate for about 15 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.