Chocolate Mashed Potato Cake recipe takes leftover mashed potatoes and turns them into a moist chocolate cake that’s so light and fluffy!
Once a holiday is over, there are always tons of leftovers. It’s nice not having to cook again for a day or so, but then it can get old eating the same thing again and again.
That’s why it’s great to have recipes that repurpose those leftovers into new dishes – like this Chocolate Mashed Potato Cake recipe that uses leftover mashed potatoes.
If you’ve never baked with mashed potatoes before, it may sound a little strange, but mashed potatoes are the key to some light and fluffy baked goods. For instance, I use them in my Amish dinner rolls to give the rolls their light texture.
The mashed potatoes work the same magic in this cake. The cake is really moist, and the potatoes also help to give it a fluffier texture.
This is the cake that my oldest daughter chooses as her birthday cake almost every year. I hope you’ll enjoy it just as much as we do!
How to make
Preheat oven to 350 F. Grease and flour a 9×13-inch baking dish. Set aside.
In a medium bowl, whisk together flour, baking soda, and salt. Set aside.
In a large bowl, beat butter and sugar together until combined.
Beat in eggs, buttermilk, and vanilla until well-combined.
Add mashed potatoes and melted chocolate. Mix until incorporated.
Stir in flour mixture until just incorporated.
Pour batter into prepared baking pan, smoothing as needed.
Bake for 35-50 minutes, or until a wooden toothpick inserted in the center comes out clean.
Let cake cool to room temperature before frosting.
TO MAKE THE FROSTING
Beat butter and powdered sugar together until well-combined.
Mix in chocolate and milk until completely incorporated. Spread over cooled cake.
Tips
Cake flour: If you don’t have cake flour, you can make a homemade substitute with this recipe. Also, to properly measure the flour, stir or sift it to break it up, lightly spoon it into the measuring cup, and level.
Butter: I use salted butter in this recipe. You can use unsalted if you prefer. “Cool room temperature” means that the butter is about 68F. The butter should dent when pressed, but the stick shouldn’t lose its shape or be smooshy.
Buttermilk: You can use regular or low-fat buttermilk. If you don’t have buttermilk, you can make a substitute with this recipe.
Mashed potatoes: Instant or regular will work. If you don’t have leftover mashed potatoes, I have a section just below that describes how to make enough mashed potatoes for this cake.
How to make a quick batch of mashed potatoes
To make enough mashed potatoes for this cake, peel one large baking potato. Cut the potato into chunks.
Place the potato chunks in a pot of cold water. There should be enough cold water to cover the potatoes by about 1 inch.
Boil the potatoes until fork tender. Drain the water and then mash the potatoes.
Other frostings that pair well with this cake
Storage
This cake can be stored, covered, at room temperature for up to 4 days. The frosted cake should be stored, covered, in the fridge.
If you’ve tried this chocolate mashed potato cake recipe, don’t forget to rate the recipe and leave me a comment below.
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Chocolate Mashed Potato Cake
Equipment
- 9×13 pan
Ingredients
Chocolate Mashed Potato Cake
- 1 ¾ cups cake flour
- 1 ½ teaspoons baking soda
- 1/2 teaspoon salt
- 1/2 cup butter at cool room temperature
- 1 ½ cups granulated sugar
- 2 large eggs at room temperature
- 1 cup buttermilk at room temperature
- 1 teaspoon vanilla extract
- 4 ounces unsweetened baking chocolate melted and cooled slightly
- 3/4 cup plain mashed potatoes warm
Chocolate Frosting
- 12 tablespoons butter softened
- 3 cups powdered sugar
- 3 ounces unsweetened baking chocolate melted and cooled slightly
- 3-4 tablespoons milk, half-and-half, or heavy cream
Instructions
To make the cake
- Preheat oven to 350 F. Grease and flour a 9×13-inch baking dish. Set aside.
- In a medium bowl, whisk together flour, baking soda, and salt. Set aside.
- In a large bowl, beat butter and sugar together until combined.
- Beat in eggs, buttermilk, and vanilla until well-combined.
- Add mashed potatoes and melted chocolate. Mix until incorporated.
- Stir in flour mixture until just incorporated.
- Pour batter into prepared baking pan, smoothing as needed.
- Bake for 35-50 minutes, or until a wooden toothpick inserted in the center comes out clean.
- Let cake cool to room temperature before frosting.
To make the frosting
- Beat butter and powdered sugar together until well-combined.
- Mix in chocolate and milk until completely incorporated.
- Spread over cooled cake.
Notes
- Cake flour: If you don’t have cake flour, you can make a homemade substitute with this recipe. Also, to properly measure the flour, stir or sift it to break it up, lightly spoon it into the measuring cup, and level.
- Butter: I use salted butter in this recipe. You can use unsalted if you prefer. “Cool room temperature” means that the butter is about 68F. The butter should dent when pressed, but the stick shouldn’t lose its shape or be smooshy.
- Buttermilk: You can use regular or low-fat buttermilk. If you don’t have buttermilk, you can make a substitute with this recipe.
- Mashed potatoes: Instant or regular will work. If you don’t have leftover mashed potatoes, I have a section above the recipe that describes how to make enough mashed potatoes for this cake.
- Nutrition facts are estimates.
Nutrition
Did You Make This Recipe?
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Adapted from Desserts From the Famous Loveless Cafe.
Originally published 4/17/17. Updated with additional photos and tips 3/8/21.
Reader Interactions
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Comments & Reviews
Sheila says
Who knew mashed potatoes would make such a delicious cake. We loved every bite.
Kate says
Thank you! I’m so glad that you liked it!
Catherine Maxey says
Great recipe. I made 2/3 recipe and got 18 cupcakes. Bake time about 18 minutes. Added 1tsp cinnamon. 1/4 tsp black pepper. 1tsp coffee crystals dissolved in the buttermilk. Used instant mashed potato’s. Great texture. Great flavor. I added about 1/4 mini chocolate chips.
Kate says
Thank you so much! This is my older daughter’s favorite cake, and I’m glad to hear that other people are enjoying it, too!
Carol Sutton says
How long will this cake keep
Kate says
Since it’s so moist, it’s best eaten in the first 2 days.
Ahmed says
Can I use white chocolate instead of the dark chocolate and add some orange zest to make an orange white chocolate cake? Or it will feel like mashed potatoes?
Kate says
Sorry, but I’m not sure how it would be with white chocolate. I don’t think it would taste like mashed potatoes, but I’m just not sure how white chocolate would taste with this cake.
Joyce Kerns says
I’m going to make this cake but I can’t have chocolate. Is there a rec ipe for a MASHED POTATO CAKE?
Kate says
Hi! I haven’t tried to make this cake without the chocolate, so I can’t say what changes would need to be made. If you can tell me what flavor of cake you’re looking for, I may be able to direct you to a recipe that would work out better for you.
Erbear says
Use carob. I’m allergic to chocolate and make carob cakes all the time (usually I use beets, not potatoes, but the idea is the same). UNSWEETENED carob is naturally much sweeter than chocolate though, so cut the sugar by at least 1/4-1/2. Though, now that I live in Hawaii and can’t afford imported carob, I use Ube. Totally different, but it’s a substitute for us no-chocolaters.
Gemma says
Totally gorgeous..My sister’s birthday is tomorrow and I need help because I want to know if I want to make the cake for a 9″inch cake tin..should I make 1/2 of the recipe or 2/3 or 3/4 the recipe??
Kate says
Thanks! I haven’t tried cutting the recipe in half, but it half of the recipe *should* work in a 9-inch round cake pan. Good luck! =)
Nada Ahmed says
I made it yesterday and it came out incredibly moist and it was a melt in mouth cake but I noticed that it needed some cocoa powder to be richer in flavor and because I like chocolate cakes without any added frosting or even drizzle so can I add some cocoa powder and omit some flour?? Please tell me the right way to do so?
Thanks in advance
Kate says
Thank you! You can try adding cocoa powder in place of some of the frosting. Unfortunately, it isn’t an exact exchange, and you need more cocoa powder to replace the same amount of flour. For instance, if you’re replacing 1/4 cup of flour, you will usually need around 1/3 cup of cocoa powder. Hope that helps! =)
nada says
can I use vegetable oil instead of butter ?
Kate says
You can! You’ll only need 1/3 cup of vegetable oil if you use that instead of the butter.
Nada says
Thanks for your help, I will give it a try and tell you but I am sure it will be gorgeous but I want to ask you if I do use the creaming method even if I use butter or just mix all the wet ingredients together then pour wet ingredients into the dry ones??
Thanks in advance
Chelsea says
I was skeptical about this cake. I didn’t know if it would take like chocolate mashed potatoes. lol But it is one of the best cakes I’ve ever made! I made extra frosting and it was so good! Thanks for the recipe. It’s a keeper!
Kate says
Thankfully, the potatoes just make the cake light and fluffy.=) Glad you enjoyed it! Thanks for taking the time to come back and leave a comment!