Sweet Potato Cake

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This richly spiced sweet potato cake tastes like your favorite fall memories. With a decadent marshmallow buttercream that comes together in just 5 minutes, there are so many things to love about this cake. Read all the way through for tips on frosting a perfectly smooth cake.

Oh sweet potato. Did anyone else grow up thinking these things were the worst?

We didn’t even serve sweet potatoes in my family, but the horror stores of this orange vegetable covered in marshmallows haunted our Thanksgiving food discussions for years.

As a kid, the idea of eating a candy covered vegetable, of all things, just seemed… wrong.

In fact, it wasn’t until many many years later that a somewhat sweet potato obsessed friend was able to change my mind while sitting in a small bakery on the southwest side of Portland.

And now, here we are, putting vegetables in cake and covering them with marshmallow buttercream. 10/10 would recommend.

How to make sweet potato cake

First, prepare your cake.

Preheat your oven to 350F and line the bottom of two 6″ cake pans with parchment paper.

In a small bowl, heat the milk and butter until melted. You want to heat this just enough so that you can stir the butter smooth, but you want to try to avoid getting it hot.

Ultimately, we want this to be about room temperature by the time we add it to the batter. You can refrigerate it to help it cool more quickly.

In the bowl of your stand mixer, whip the eggs and granulated sugar on high until light and fluffy, and the sugar has mostly dissolved.

Add the milk/butter mixture and sweet potato, mixing on low until just combined.

Pro tip: If you can’t buy sweet potato puree, here’s how to make your own.

Scrub two sweet potatoes, poke a few holes in them with a fork, and bake them at 350F for 1-2 hours, or until tender. Once the sweet potatoes have cooled enough to handle, peel off the skin and puree them in a blender.

Gently fold in the rest of the ingredients, and divide batter between three 6″ pans. Bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean.

Once the cake pans are cool enough to handle, turn the cakes out onto plastic wrap, seal and place in the refrigerator.

Second, make the caramel sauce.

In a small saucepan, heat the granulated sugar for the caramel over medium-high heat stirring constantly until completely melted and lump free.

Add butter (be careful not to let the splatter hit you; It’s hot!) and continue cooking and stirring until the butter is melted.

Add the heavy cream and allow to bubble for an additional minute, stirring constantly.

Remove the pan from the heat and allow to cool completely at room temperature.

Pro tip: If you want to skip the homemade caramel, store bought works, too. Just keep in mind that store bought caramel sauce is thinner and will run down the sides more quickly. As you can see, I used store bought in the photos above.

Third, make your frosting.

In the bowl of a stand mixer, beat the softened butter and marshmallow fluff until smooth.

With the mixer on low, add the powdered sugar slowly. Increase speed to high and beat until smooth (a minute or two).

Pro tip: If the frosting has a lot of air bubbles, reduce the speed to low and beat for 3-5 minutes, or until smooth.

Finally, assemble the cake.

To assemble the cake, alternate between layers of sweet potato cake and layers of frosting.

Crumb coat the entire cake and allow to set in the refrigerator until firm. This will lock in all the crumbs and keep that white frosting free of any orange crumb chunks.

Frost the top and sides of the cake and refrigerate the cake for about 15 minutes or until cool and firm. A cold cake will help slow down the caramel drip.

Heat your caramel just enough so it’s not too thick but not hot (about 10 seconds in the microwave), and gently pour it over the top of the cooled cake.

Use an offset spatula or knife to work it out towards the edge and over the sides.

Garnish the cake with fresh fruit like figs, grapes and blackberries, or anything else you have on hand.

Tips for making sweet potato cake

• Making your own sweet potato puree: Wash and prick two sweet potatoes and bake them at 350F for 1-2 hours, or until tender. Once cooled, peel off the skin and puree them in a blender.
• Measure your batter: Making even layers of cake start with measuring your batter. For this recipe, that means about roughly 12 oz of batter per pan (for three pans).
• Chill your cake: Cool cake is easier to cut and handle, so chilling your cake for a short while before use will make this process easier.
• Air bubble-free frosting: If the frosting has a lot of air bubbles, reduce the speed on your stand mixer to low and beat for 3-5 minutes, or until smooth.
• The trick to a smoothly frosted cake: You’ll need a rotating cake stand and a bench scraper. Place the small end of the bench scraper on the cake stand, long end against the frosting and turn the table. Once excess frosting is removed, heat the scraper in hot water, wipe and drag around the outside of the cake.
• Store bought caramel substitute: Store bought caramel can be substituted for homemade. You’ll need about 1/3-1/2 cup for this recipe.
• Storage: This cake will keep at room temperature, uncut, for 3-4 days. For best results, cover it with a plastic lid, bowl or place it in a cardboard box.
• Storing cut cake: Once your cake is cut, you’ll want to protect the exposed cake area. The easiest way to do this is with a piece of plastic wrap or two.

Did you make this recipe? I’d love to hear how it went in the comments below. Better still, snap a photo and tag it on Instagram with #thesimplesweetlife. I love seeing your creations!

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If you liked this recipe, you might also like…

• Peaches and cream cake
• Caramel macchiato cake
• No-churn sweet potato ice cream

Update Notes: This post was originally published in November of 2015 but was republished with updated photos, directions and tips in August of 2019.

Oh hey, you made it all the way to the bottom! And you probably noticed that this post is a 4 year old post that I recently updated.

Normally, this is where I make a comment about how much my food photography has changed, but today, I want to spotlight cake decorating.

I often talk about food photography and styling as though they’re separate from things like cake decorating, but in reality, they’re really not.

I’ve learned over the years that if you really want to take your photography and styling to the next level, you need to be thinking about how you’re going to decorate and style your cakes all the way back at the recipe development phase.

The first time around I went with dollops of frosting and chocolates with hard edges. It made for a visually interesting cake, but it lacked the organic, naturally feeling I went for in this cake.

This cake looks like something you’d serve at Thanksgiving, not something you’d take an eye out on. 😂 Have a look for yourself!

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