I love to collect vintage cookbooks - there was even an article about my cookbook collection in Carolina Home + Garden magazine. When I get a new old cookbook, the first thing I do is read through every single recipe. That is how you find gems like this chocolate potato cake, also known as surprise chocolate cake.
While you may think it's a little strange to add mashed potatoes to chocolate cake, let me tell you that is makes the moistest cake. Potato starch is in fact known for creating moist bakes. Since I love sweet potatoes, I decided to try out this recipe with mashed sweet potatoes instead to capture not only the moist texture but the yummy caramelized flavor that you get from sweet potatoes, plus sweet potatoes pair perfectly with chocolate.
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Origins of Chocolate Potato Cake
This recipe was adapted from a book called Gregory Cooks. This cookbook was created by Gregory Elementary School, located in Wilmington, NC, as a school fundraiser.
I so enjoyed flipping through this book for recipe inspiration. There are a lot of gems in here. I'm not sure if this book was written by students or just had no editing, but there are quite a lot of unusable recipes in here. The way many of these recipes are written would spell disappointment for an inexperienced baker. The first one that caught my eye was "Surprise Chocolate Cake" submitted by LeRoy Johnson.
There are a lot of surprises about this cake, like it has no chocolate and no flour, so I'm not sure how it turns into a chocolate cake. Pour LeRoy had to add sugar packets to mashed potatoes and margarine and pretend it was chocolate cake. Not to mention a complete lack of cooking instructions.
I spent some time researching the "surprise cake", which seems to be a very old recipe and a way of bypassing the use of flour during war rationing times. So perhaps LeRoy's cake recipe was not all wrong. I decided to modernize this recipe, make it gluten free and dairy free and the results were delicious!
Ingredient Notes
- Gluten Free Flour Blend - I use Bob's Red Mill 1-to-1 flour for most of my recipes. You can use your favorite gluten free flour blend, but ensure it contains xanthan gum or a similar binder.
- Unsweetened Cocoa Powder - I use Hershey's brand unsweetened cocoa powder, which is gluten free.
- Baking Powder - This leavening agent is used to help the cake to rise and have a lighter texture.
- Salt - A little salt is needed to balance the sweetness of this cake.
- Cinnamon - I think cinnamon is the perfect compliment to both chocolate and sweet potatoes. Just a little is used here, so it's subtle but wonderful.
- Sugar - White sugar is used to sweeten this cake. We don't need brown sugar since there is already a lot of moisture from the sweet potatoes.
- Eggs - This cake is made using the sponge cake method, where the eggs are first combined with the sugar instead of creaming sugar with fats. Because of that, I haven't tried this recipe with an egg replacement.
- Oil - I use extra light olive oil in all of my cooking and baking, but any light flavored cooking oil will work fine. Melted coconut oil would work as well.
- Vanilla Extract - A little bit of vanilla is used to sweeten the flavor of the cake.
- Chopped Chocolate - I love Scharffenberger chocolate for baking. Use a good quality chocolate bar here, not chocolate chips.
- Sweet Potatoes - Cook and mash sweet potatoes with no added butter or other ingredients. I used some leftover baked sweet potatoes and mashed them for the cake. If you're cooking sweet potatoes just for this cake, make sure to let them cool to room temperature before adding them to the cake batter.
- Non-Dairy Milk - I use unsweetened coconut milk in my cooking and baking. Any non-dairy milk will work fine. If you're not dairy free, use dairy milk in the same measure.
See the recipe card below for full ingredient list with measurements.
Substitutes & Variations
- No Sweet Potatoes - Replace mashed sweet potatoes with regular mashed potatoes instead.
- Not Dairy Free - Replace non-dairy milk with whole milk in the same measure.
How to Make a Chocolate Potato Cake
This is a very easy cake to make, although I do recommend using a mixer, either handheld or a stand mixer.
STEP 1: Add the chopped chocolate to a microwave safe bowl. Melt on 50% powder for about 2 minutes and stir until smooth. Set aside to cool.
STEP 2: Add the gluten free flour, cocoa powder, baking powder, cinnamon and salt to a small mixing bowl. Whisk together until combined.
STEP 3: Add sugar and eggs to the bowl of an electric mixer. Beat with the whisk attachment until the mixture reaches the ribbon stage, about 5 minutes.
STEP 4: With the mixer still running, slowly pour the oil into the bowl.
STEP 5: Add the mashed potatoes, melted chocolate and vanilla extract to the cake batter. Mix for 1-2 minutes until incorporated.
STEP 6: With the mixer on low speed, add half of the dry ingredients followed by half of the milk. Repeat with the remaining ingredients. Mix just until incorporated.
STEP 7: Spread the cake batter into a parchment lined baking dish. Then bake!
Top Tip
Bake the cake until the top springs back when gently poked. This is a very moist cake, so be careful not to under bake as the center will sink in as it cools.
Storage
Store leftover cake in an airtight container at room temperature for up to 3 days.
Serving Suggestions
- Sprinkle the top of the cake with powdered sugar
- Serve with a dollop of whipped cream or a scoop of vanilla ice cream
- Serve with fresh fruit
More chocolate recipes to consider:
If you try this recipe, please leave a 🌟🌟🌟🌟🌟 star rating and let me know how you liked it in the comments below.
Recipe
Gluten Free Chocolate Potato Cake
Ingredients
- 2 ounces Dark Chocolate chopped
- 1 ½ Cup Gluten Free 1-to-1 Flour Blend I use Bob's Red Mill
- ½ Cup Unsweetened Cocoa Powder
- 1 ½ teaspoon Baking Powder
- ½ teaspoon Cinnamon
- ½ teaspoon Salt
- 1 ½ Cup Sugar
- 2 Eggs
- ½ Cup Olive Oil
- 1 teaspoon Vanilla
- 1 Cup Mashed Sweet Potato plain
- ½ Cup Non Dairy Milk
Instructions
- Preheat oven to 350 degrees. Line a 9x9 pan with parchment paper.
- Place the chopped chocolate in a microwave safe bowl. Heat on 50% power for 2 minutes. Stir until all pieces are melted. Set aside to cool.2 ounces Dark Chocolate
- In a large bowl, combine flour, cocoa powder, baking powder, cinnamon, and salt. Stir together until well combined. Set aside.1 ½ Cup Gluten Free 1-to-1 Flour Blend, ½ Cup Unsweetened Cocoa Powder, 1 ½ teaspoon Baking Powder, ½ teaspoon Cinnamon, ½ teaspoon Salt
- In the bowl of an electric mixer fitted with the whisk attachment, combine the sugar and eggs. Beat until it is lightened in color, increased in volume and creates a ribbon. This will take about 5 minutes.1 ½ Cup Sugar, 2 Eggs
- With the mixer still running, slowly pour in the oil.½ Cup Olive Oil
- Add the melted chocolate, sweet potatoes and vanilla and mix for about 2 minutes until well combined. Scrape down the bowl.1 teaspoon Vanilla, 1 Cup Mashed Sweet Potato
- Turn the mixer to the lowest speed. Add half of the dry ingredients, followed by half of the milk. Repeat with the remaining ingredients mixing only until just combined.½ Cup Non Dairy Milk
- Pour the batter into the prepared pan. Bake for 35-40 minutes, until the top springs back when gently poked. This is a very moist cake, so be careful not to under bake as the center will sink.
- Remove from the oven and cool for 15 minutes in the pan. The remove the cake from the pan and cool on a wire cooling rack.
Notes
Tiffany is the recipe developer, stylist and food photographer behind Well Fed Baker. As a lifelong baker who had to go gluten free and dairy free in 2016, Tiffany strives to share allergen friendly recipes that never feel like they are free from anything.
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