Super light and fluffy Korean sweet potato cake made with a light sponge and creamy sweet potato filling. This cake is so good you would never know it’s made with sweet potatoes. Super popular in South Korean bakeries, this goguma cake is not overly sweet and just delicious!
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Korean Sweet Potato Cake is a popular dessert in South Korea that’s as delicious as it is pretty. In Korean it’s called 고구마 케이크 (goguma cake), which literally means ‘sweet potato cake’.
This unique cakeis made with soft layers of sponge cake and a creamy sweet potato filling. Covered in airy whipped cream, brings out the natural sweetness of real sweet potatoes.
Goguma cake is probably my favorite type of cake because it’s not overly sweet. Korean sweet potatoes are very different from the ones in Western countries, as they’re really naturally sweet. They are perfect for desserts, and this Goguma Cake is the proof!
The sponge is as fluffy as a cloud, and the sweet potato cream is incredibly smooth and light. This Korean sweet potato cake is not too sweet, and it relies mostly on natural flavours and sweetness. Perfect for Asian dessert lovers!
For more sweet Korean desserts, make sure to try these traditional Korean Twisted Donuts, the famous Korean Sweet Pancakes or this adorable Korean Lunchbox Cake!
Why you'll love this recipe
- Natural sweetness: This Korean sweet potato cake is not overly sweet, as it relies mostly on the natural sweetness of the potatoes. It’s the perfect level of sweetness!
- Light and fluffy: The sponge in this Goguma Cake is one of the lightest cakes ever! It has an incredibly light and fluffy texture just like a chiffon cake, so it’s like eating a cloud.
- Unique Flavor: Combining sweet potatoes with vanilla, cream, and a light sponge cake creates a distinctive flavor that will impress all your guests!
What is Goguma?
Goguma (고구마) is a type of Korean sweet potato known for its sweet, nutty flavor and golden yellow flesh. Unlike the orange-fleshed American sweet potatoes common in Western recipes, goguma has a chestnut-like flavor and is denser, with less moisture.
These Asian sweet potatoes are slightly smaller with brownish or purple skin. They can be found in most Korean grocery stores, especially in the autumn and winter months when they’re in season.
When cooked, goguma develops a creamy texture, so it’s perfect for baking into desserts. Goguma is often sold by street vendors as a sweet treat, as a healthier alternative to candy.
Some popular dishes made with goguma are this Korean sweet potato cake, Korean sweet potato latte or Goguma mattang 맛탕 (candied sweet potato).
Ingredient round-up
- Korean Sweet Potatoes – Known for their natural sweetness, they’re ideal for the creamy sweet potato filling. Make sure you use either Korean sweet potatoes (also known as goguma) or Japanese sweet potatoes. Regular sweet potatoes don’t work as well in this recipe.
- Whipping Cream – Used as a frosting to cover the cake. It’s super light and works well with the airy cake.
- Eggs – The sponge is super fluffy because a lot of air is whipped into the eggs.
- Vanilla Extract – Use high quality vanilla extract or vanilla bean paste.
- Cake Flour – Essential for the soft, tender texture of the sponge. Also known as Type 000 flour, cake flour is much softer and ideal for light and airy sponges.
How to make this recipe
Prepare the Sweet Potato Filling
- Peel and cube the sweet potatoes, then microwave until tender.
- In a saucepan over medium heat, mash the cooked potatoes with heavy cream, butter, and condensed milk until thick and creamy. I like to leave some chunks of sweet potato for texture. Cool completely before assembling.
Bake the Sponge Cake
- In a large bowl, whip the eggs, sugar, and honey until pale and fluffy, reaching stiff peaks. No need to separate the egg whites, but make sure you whip the eggs really well.
- Gently fold in sifted cake flour and melted butter until just combined. Pour the batter into the pan and bake until golden brown.
Assemble the Cake
- Add sweet potato filling on the first sponge layer, evening it with a spatula.
- Add the second sponge layer, then also cover it with goguma filling. Top with the last cake sponge.
- Frost the entire cake with whipped cream and chill for 1-2 hours before serving.
- Optional, for a Korean bakery look, ground sponge cake crumbs and add on top for decoration.
Flavor Variations
- Chestnut Paste – A thin layer of chestnut paste over the sweet potato filling adds a complementary nutty sweetness.
- Cinnamon or Nutmeg – Sprinkle a hint of cinnamon or nutmeg in the sweet potato filling for a cozy flavor.
- Cream Cheese Filling – Add a layer of cream cheese for a slight tang that pairs well with the sweet potato’s natural sweetness. Or use White Chocolate Cream Cheese Frosting to cover the cake.
- Candied Sweet Potatoes or Walnuts – Garnish the cake with candied sweet potato slices or walnuts for a lovely crunch.
Success Tips & Tricks
- Fluffy eggs: It’s important to whip up the eggs really well until very fluffy. If the eggs aren’t aerated enough, the cake sponge will be dense.
- Room temperature ingredients: The eggs whip much better if they’re room temperature, and the ingredients blend better together.
- Don’t Overmix the Batter: To keep the sponge cake light and airy, carefully fold the flour into the whipped eggs using a rubber spatula. Overmixing can deflate the batter, resulting in a denser cake.
- Individual Cake Tins: For even layers and the best rise, use three separate 6-inch cake pans. This ensures each layer bakes evenly, giving you a professional-looking cake with minimal slicing needed.
- Creamy filling: Older sweet potatoes or certain varieties can have a drier texture, which can affect the texture of the filling. If the sweet potato paste seems too thick or dry, stir in a splash of milk or heavy cream while mashing to achieve a smoother, creamier consistency.
- Cool Each Component Before Assembling: Allow both the sponge cake and sweet potato filling to cool completely before assembling. For the best presentation and clean layers, chill the cake for at least an hour before slicing.
Frequently asked questions
Store in an airtight container in the refrigerator for up to 3 days.
Yes, you can also use Japanese sweet potatoes, but they may vary in sweetness and texture. I do not recommend using American sweet potatoes, as they are very different and not suitable for this type of cake.
Purple sweet potato is different from Korean sweet potato. Although you can use it, the flavor and texture will be very different from the original Goguma Cake.
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Recipe
Korean Sweet Potato Cake with Whipped Cream (고구마 케이크)
Ingredients
Sponge Cake
- 4 large eggs room temperature
- 115 grams sugar
- 15 grams honey
- 110 grams cake flour*
- 4 grams baking powder
- 15 grams melted butter
- 25 grams milk
- 1 ½ teaspoon vanilla extract
Sweet potato filling
- 375 grams Korean sweet potatoes
- 200 grams heavy cream
- 40 grams butter
- 75 grams sweetened condensed milk*
- 1 teaspoon vanilla extract
- splash of milk if potatoes are too dry
Decorating
- 240 grams whipping cream
- 30 grams powdered sugar
Instructions
Sponge Cake
- Prepare 3 cake tins (6-inch) by greasing and lining them with parchment paper. Preheat the oven to 325F (160C) fan-assisted.
- In a large mixing bowl, add the eggs, sugar and honey, then whisk until the sugar dissolves.
- Using an electric mixer, whip up the eggs until pale and tripled in volume. They should hold a stiff peak and be very fluffy.
- Separately in a bowl, whisk the cake flour and baking powder to combine well. Using a large sieve, sift the flour mixture into the eggs.
- Using a spatula, carefully fold the flour into the whipped eggs, without deflating the air.
- In a small bowl add the melted and cooled butter, milk and vanilla extract. Add a little of the cake batter into the butter mixture, combining it well. Pour everything back into the large cake batter bowl.
- Once again, use the spatula to gently fold all the ingredients together, ensuring the batter remains fluffy and airy.
- Pour the batter into the lined cake tins and bake for 15-20 minutes or until a skewer comes out clean. Do not open the oven for the first 15 minutes of baking.
- Once baked, let cool in the cake tin for 5 minutes, then transfer to a cooling rack and cool down completely. Once cold, cover in plastic wrap and chill in the refrigerator for 2-3 hours.
- Using a cake leveller or serrated knife, cut off the top layer to make it completely flat. Reserve this top layer for later. Cut the remaining cake into 3 equal horizontal slices.
Sweet potato filling
- Peel the sweet potatoes, then cut into ½ inch small cubes. Add the potato cubes to a microwave-safe bowl, then cover with plastic wrap and poke a few holes. Microwave for 5 minutes or until soft.
- Transfer the potato cubes to a saucepan, along with heavy cream, butter and sweetened condensed milk.
- Cook over medium-low heat until the mixture starts bubbling. Reduce the heat to low and cook for 3-5 minutes.
- Use a potato masher or a fork to mash the potatoes until the mixture turns into a paste. Keep cooking until the potato paste looks thicker and sticky, but still slides off the potato masher. If it’s too thick, add some cream or milk to thin it. Add the vanilla extract and mix well to incorporate.
- Cool down potato filling completely, then cover and refrigerate for 1-2 hours.
Assembling the sweet potato cake
- If the cake layers aren’t even, use a bread knife to level them out.
- Place the first cake layer on a cake board or stand. Add a thick layer of sweet potato filling on top of the sponge, then spread it evenly with a cake spatula.
- Sandwich the filling with another cake layer. Repeat the process of topping with sweet potato filling. Add the last cake layer on top of the filling.
- For the frosting, whip up the cream and sugar until medium-stiff peaks. Cover the cake with whipping cream, using a cake spatula to smooth it out. For a seamless finish, you might need two coats of whipping cream.
- For decoration, crumble some cake scraps until it resembles fine sand. Sprinkle it on top of the cake and at the base if desired.
- Add any remaining whipping cream to a piping bag fitted with decorative nozzle. Pipe dollops of cream on top of the cake for a more refined look.
- Chill the cake in the refrigerator for 1-2 hours before cutting.
Notes
- I recommend using a kitchen scale in grams for more accuracy. The cups used for the conversion are standard US customary cups (1 cup flour = 136g). There are many different types of cups across the globe, which is why I strongly recommend using grams instead.
- Nutritional value is estimative and it's calculated per serving (this recipe makes one 6-inch cake, or 8 small slices).
- Cake flour - also known as Type 000 flour.
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