Transform a traditional Thanksgiving side dish into the perfect dessert with this Sweet Potato Cake with Marshmallow Frosting.
I didn’t know this combination was even a thing until a couple of years ago, but apparently sweet potato casserole with marshmallows is a huge thing at Thanksgiving. Or at least it is in the US. I don’t think anyone I know in Canada has ever had it as part of their Thanksgiving dinners. Are we missing out or what?!
The most interesting thing about this dish is that it’s not meant to be a dessert, but a Thanksgiving dinner side dish. Craziness! Though to be honest, it sounds delicious. I’ve never had the real thing, but I thought why not do a take on it with this Sweet Potato Cake with Marshmallow Frosting.
I was super intrigued to know how this bizarre combination of a dish came about. Hilariously, it turns out it originated from the marshmallow industry as a way to sell more marshmallows! Apparently, back in 1917, the marketing team at Angelus Marshmallows hired someone to create a recipe book that focused on marshmallows as one of the ingredients. The sweet potato casserole was one of those recipes, and it’s clearly still going strong today. Now that’s marketing done right.
Whether you love the original or not, I hope that this Sweet Potato Cake will be either a loving tribute or a grateful alternative to the classic Thanksgiving dinner staple.
If you’ve never had sweet potatoes before, you really need to give them a try. They are delicious! I’ve had them as fries (dipped in a creamy dill sauce – yum), mashed up with some butter & brown sugar, or just steamed on their own with some salt and pepper. Each and every combination is a winner. Yes, even the one with the marshmallows. Especially when it’s in the form of a cake!
How to Make this Sweet Potato Cake
To make this Sweet Potato Cake, I modified my Pumpkin Spice Latte Cake recipe and used canned sweet potato puree, instead of pumpkin. You could certainly make your own puree with some mashed up cooked sweet potatoes if you prefer.
I paired the cake with homemade marshmallow fluff as frosting to keep it similar to the traditional Thanksgiving dish.
Unfortunately, I did not make nearly enough marshmallow fluff. While this cake looks pretty and perfect, I can assure you things aren’t always what they seem. There are no rosettes on the back of it (lol). I knew I would run out, so I did what I could and covered the critical areas (read: I was too lazy to make more fluff). The recipe has been adjusted to make the correct amounts.
I am happy to report that there were no issues with my kitchen torch this time. That’s twice in a row now that I’ve managed not to burn myself or set myself on fire. Rest assured though, I’m always nervous when I go to use it.
This Sweet Potato Cake is moist and delicious. The cake itself has a comforting Fall spice flavour, reminiscent of pumpkin, but not quite. The cake is not super sweet, so it pairs really well with the sweet but light as air marshmallow frosting.
If you love Pumpkin Cake I think you’ll love this one too. I hope you enjoy my tribute to this wacky Thanksgiving side dish!
Tips for this Sweet Potato Cake with Marshmallow Frosting:
- The recipe as-is will also work in three 6″ pans. For three 8″ pans, 1.5x the recipe.
- To make cupcakes, all you need to do is reduce the baking time — start checking at 15mins or so.
- The cooled cake layers can be baked ahead of time, double wrapped in plastic wrap, and frozen for up to 3 months. Take out 2-3 hours before assembly.
- You can cook and mash your own sweet potatoes if you’d prefer to use that instead of canned sweet potato puree.
- You don’t have to torch the marshmallow, but it will help “set” it (and it tastes delicious).
- Do NOT use store-bought marshmallow fluff. It is too runny and will not pipe well.
- Ideally, serve the cake the same day — the marshmallow fluff inside the cake will soften and turn runny the longer it sits. This is not bad by any means, but maybe less aesthetically pleasing.
- Learn how to keep your cakes moist using Simple Syrup.
- To help ensure your cake layers bake up nice and flat, check out my How to Bake Flat Cake Layers post!
Sweet Potato Cake with Marshmallow Frosting
Ingredients
Sweet Potato Cake:
- 2 1/2 cups all-purpose flour
- 2 1/4 tsp baking powder
- 1 tsp ground cinnamon
- 1/4 tsp ground nutmeg
- 3/4 tsp salt
- 6 Tbsp unsalted butter melted, cooled
- 6 Tbsp vegetable oil
- 1 cup granulated sugar
- 1 cup light-brown sugar packed
- 1 1/2 cup sweet potato puree
- 3 large eggs room temperature
- 1 tsp vanilla
Marshmallow Fluff:
- 2/3 cup water
- 1 1/2 cup granulated sugar
- 1 1/2 cup light corn syrup
- 6 large egg whites room temperature
- 1 tsp cream of tartar
- 2 tsp vanilla
Instructions
Sweet Potato Cake:
- Preheat oven to 350F and grease & flour two 8" cake pans.
- In a medium bowl, whisk together flour, cinnamon, nutmeg, baking powder, and salt.
- In a large bowl, whisk together sugars, melted butter, oil, sweet potato, and eggs.
- Add dry to wet and mix until just combined.
- Divide batter evenly between prepared pans and bake until a toothpick inserted into the center comes out mostly clean (approx. 35-40 mins).
- Cool in pans on wire rack for 10mins, then turn out onto wire racks to cool completely.
Marshmallow Fluff:
- Place water, sugar, and corn syrup in a medium saucepan. Stir to combine.
- Insert a candy thermometer into the pot and heat over medium-high. Do not stir from this point on as crystals will form.
- Ensure mixer bowl and whisk are completely grease free.* Place egg whites and cream of tartar in the bowl of a stand mixer.
- When the sugar syrup reaches about 225°F, start whipping the egg whites to soft peaks.
- When the whites are ready, the sugar syrup should be at 240°F. Remove from the heat, turn mixer to medium and very slowly and carefully pour the sugar syrup into the whites in a thin, steady stream.**
- Once all of the syrup is in, set mixer to medium/high and continue whipping. The whites will deflate at first, but they will thicken and fluff up.
- Continue to whip for 7-8 minutes, or until the mixture is thick and glossy. Add in vanilla and whip until the fluff has cooled.
Assembly:
- Place one layer of cake onto a serving plate or cake stand. Top with 1 cup marshmallow fluff. Spread evenly. It will be thick and sticky.
- Place remaining layer on top and do a thin coat of marshmallow all around the cake, just to hide any dark bits of cake.
- Using a 1M piping tip. Pipe rosettes along the sides and top of the cake. Torch with a kitchen torch if desired.***
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Notes
** The sweet spot for this is getting the stream right between the whisk and the sides of the bowl, so the syrup doesn't get splashed by the whisk.
*** The torching will help set the marshmallow. Ideally serve same day as the marshmallow fluff inside the cake will soften and turn runny. This is not bad, by any means, but maybe less aesthetically pleasing.
Originally Published on Oct 15, 2017
Lola Osinkolu | Chef Lola's Kitchen says
Wow, this combination is definitely a new one!
Olivia says
I hope you try it! 🙂
Jean says
Not a thing in Canada! Where did you get that idea? I live in Ottawa and we’ve had that in the fall and winter all my life, and I’m 68. We cover a baking pan of hot cooked mashed squash with marshallows and brown it in a hot oven. Delicious. That’s our version – squash, not sweet potatoes.
Olivia says
Hi Jean! I am quickly being schooled by many Canadians about this! I had honestly never even heard of it until I was WELL into my 30’s. I feel like I missed out! I need to try it for this years Thanksgiving 😀
Angel says
I made this today for my sister’s birthday and it turned out beautifully! She doesn’t like super-sweet desserts so I thought this would be perfect. It was easy to put together, and gave me a good excuse to buy a torch. 🙂 Thanks for the recipe!
Olivia says
Hi Angel! Yay! So happy you loved it 🙂 Thanks for the feedback!
Nicole says
I actually want to make this cake with actual sweet potatoes ..what would be the amount I would need for that rather than using a can .. like 2 or 3 sweet potatoes ?? I really want to make this it is so delicious but I want to use the real stuff
Olivia says
Hi Nicole! It depends on the size of the potatoes I suppose. However much you’d need for 1.5 cups mashed — I would go for 3 to be safe! I worry they will be a bit dry though and affect the texture. The puree was quite moist — the consistency of canned pumpkin. If you do use whole sweet potatoes I would add a bit of water to them to moisten the mash — so that the cake doesn’t turn out too dry or dense. Let me know how it turns out! 🙂
Glenda says
Can dark corn syrup be used as well?
Olivia says
Hi Glenda! That should work fine but will tint the marshmallow slightly.
Amanda Davis says
Could I use marshmallow fluff if I dont want to pipe the rossettes?
Olivia says
Hi Amanda! You mean store bought? I think it will be too runny and would likely slide down the cake 🙁
Amanda says
Thank you!
Stephanie says
Hi Olivia –
Do you think the marshmallow fluff would do ok if I added some food color? I’d love to make this for my daughters birthday – but wanted to add a splash of color.
Olivia says
Hi Stephanie! I would use color gels, but it should be fine!
Arceli says
Hi Olivia,
This cake looks delicious and the rosettes are gorgeous🤗
And also I am so glad that you checked out my cake photos that I sent to your email🤗
Do you think I can use this recipe or your coconut cake recipe to make a purple yam(ube) cake? I already tried 4 different purple yam cake recipes and they all turned out not so good (hard and dry, blant taste)
All of your cake recipes that i tried ( mocha,strawberry,oreo)
turned out the best,amazing and delicious..
I hope and how i wish that someday in the future you feature a purple yam cake 😂😂
Take care and have a wonderful day.
Olivia says
Hi Arceli! I would try this recipe with the ube. I’ve never baked with it myself, so can’t say for sure, but I think it’s similar to a sweet potato so should work. Let me know how it works out!
Gina says
Is there a substitution for the corn syrup? I cannot have corn syrup, and I thought maybe honey might work? Thoughts? This cake looks beautiful!!
Olivia says
Hi Gina! I’ve never used honey in it but you can give it a try!
Amanda says
Olivia,
I love making your beautiful cakes. Thanks for having this blog. This cake looks especially beautiful and perfect for Thanksgiving. Anyway you would do a tutorial video on how you make the roses on this cake?
Olivia says
Hi Amanda! Thank you so much for your sweet comments. I don’t have a tutorial video yet, but I’ll add it to my list! You can find some online if you search for “rosette cake” though 🙂
Meg | Meg is Well says
This cake is beyond gorgeous! And I love how you took inspiration from a Thanksgiving side dish. I have sweet potato casserole every year.
Olivia says
Thanks so much Meg!! xo
Cindy Rodriguez says
I love the pairing of sweet potatoes with marshmallows for this cake. Genius! Plus it’s so gorgeous that it would be my equivalent of giving someone a bouquet of flowers. It is truly gorgeous! At least from the front. Ha!
Olivia says
Aww, thank you so much Cindy! xo
paula says
Que bolo mais lindo! Dá pena cortar,mas deve ser muito saboroso, gostaria de fazer um desse jeito para a festa de casamento dos meus pais, vou ver se consigo alguém para fazer seguindo a receita, gostei de mais!
Olivia says
Thanks so much, Paula! I hope you like it 🙂
Sandra says
This recipe looks so special,a show stopper! Can u use prepared marshmallow fluff, if yes , how many cups would I need?
Olivia says
Hi Sandra! I do not recommend using store-bought fluff. It’s way too runny/thin and won’t pipe well.