So I have a confession to make. This delectable looking confection that you see in the photo above was a complete and utter failure. I had set out to make a dense fudgy gluten-free brownie, but somewhere along the line, my calculations went awry and I ended up with this disappointment.
It all started off well, after mixing everything together, I had a rich velvety batter with a dark chocolate brown hue. A few minutes in the oven, and my apartment was brimming with the aromas of chocolate and butter and I could almost taste the dense brownie melting on my tongue. But after 25 minutes, I opened the door, crestfallen to find a cake that had almost doubled in height. A brownie this was not.
By the time I'd worked my way through the five stages of grief, my maverick cake had cooled, and I decided to have a bite. Cutting into it, I was greeted by a spongy uniform crumb that literally glistened with moisture. It wasn't a brownie to be sure, but it sure looked a lot like a chocolate cake!
Ultra-moist, with a fine crumb and intense chocolate flavor, this gluten-free chocolate cake is delicious on its own, but slathered with a maple cream cheese frosting, it's divine. What's most remarkable though is the fact that there is no flour (wheat or otherwise) in this cake.
The starch comes from sweet potatoes, making it gluten-free, and since sweet potatoes are packed with vitamins A and C, fiber, calcium and iron, it's certainly more nutritious than your average chocolate cake. Better yet, sweet potatoes are naturally sweet and are good at retaining moisture. This means you can get away with using less sugar and butter while still getting a rich, sweet chocolate cake.
I used Japanese sweet potatoes, which are characterized by their ruby red skin and sweet yellow flesh. With a lower moisture content and higher starch content than the orange fleshed variety, these sweet potatoes are perfect for baked goods. I've seen them at farmers markets, Whole Foods and Fresh Direct, but if you can't find them at your local supermarket, try visiting an Asian grocery store.
This chocolate cake is so good and easy to make, it's become a staple in my kitchen, and I've even used it as the base for a birthday cake. Layered with whipped cream, and covered in a rich ganache it's hard to believe that it all started with a mistake.
📖 Recipe
Units
Ingredients
- 700 grams Japanese sweet potato (you want to end up with 640 grams grated)
- 2 large eggs
- 6 tablespoons cultured unsalted butter (melted)
- 125 grams granulated sugar (~⅔ cup)
- 80 grams unsweetened cocoa powder (~⅔ cup)
- 1 teaspoon vanilla extract
- ⅛ teaspoon salt
- 2 teaspoons baking powder
- 200 grams cream cheese (at room temperature)
- ¼ cup grade b maple syrup
- 1 teaspoon vanilla extract
Instructions
- Line an 8" x 8" square cake pan with parchment paper and preheat the oven to 375 F (190 C).
- Peel the sweet potato and then grate it into a blender along with the eggs, melted butter, sugar, coco powder, vanilla and salt. Blend until the mixture is smooth and free of lumps.
- Add the baking powder and blend until just combined (don't overmix). The baking powder leavens the batter helping it to rise but if you over mix it all the of the leavening powder will be used up before your brownie makes it into the oven.
- Pour the batter into your prepared pan, flatten off the top and bake until a toothpick inserted into the center comes out clean (30-40 minutes).
- Let the cake cool for 15 minutes in the pan on a wire rack and then remove the pan, allowing the cake to cool completely.
- For the frosting just whisk together the cream cheese, maple syrup and vanilla until smooth, and spread it on top.
Aeriol Nicols says
What would you use to substitute for the cream cheese. Other than tofu. I am dairy and soy intolerant. Thanks
Marc Matsumoto says
Try soaking raw cashew nuts in water overnight and then blending them until smooth with just enough of the soaking liquid to make them blend.
Maho Morita says
What a brilliant idea to use sweet potato to retain moisture! Any kind of cocoa powder (Dutch-processed/Natural) will do?
Marc Matsumoto says
Thanks SJMF! I used dutch-processed for its color and milder acidity, but you could probably use natural as well.
kimmiddleton says
Do you think Canned pumpkin could substitute? I've used it in a few slice and brownie recipes and it works great - thoughts? Have never seen Japanese sweet potato in Australia, so thinking about what we can use (Japanese pumpkin, purple sweet potato? or as I mentioned canned pumpkin - from USA 🙂
Marc Matsumoto says
Hi Kim, I wouldn't recommend using canned pumpkin because it does not have a lot of starch, Japanese pumpkin could work (though I haven't tried it), and of the options you mentioned I think purple sweet potato would work the best. If you try it, let us know how it goes.
cheryl says
Do you think I would be able to replace the butter with oil eg. canola or other vegetable oil?
Marc Matsumoto says
Hi Cheryl, that will technically work, but you're not going to get the butter flavor without the butter if you use oil.
Anna says
This is grated raw sweet potato you used?
Marc Matsumoto says
Yep, just be sure you're using a variety of sweet potato that's relatively high in starch (the orange fleshed variety will not work).
kimmiddleton says
Hi Marc, made this today with Japanese pumpkin, but because I don't have a scale, I estimated the amount of grated pumpkin at about 2 cups. Could you please tell me what the correct measurement would be in cups? Also had to tweak it and added 1/2 cup of almond meal and an extra egg, then totally forgot the butter as it was in the microwave melting! The end result was a chocolate brownie cake texture and the butter wasn't missed as it was so moist and full of chocolate flavor. Kids loved it, so I'm happy that I have a way to get some pumpkin into them 😉
Marc Matsumoto says
Glad to hear you still enjoyed it. I'm going to need to make this again to get you a cup measure, but my gut is that it's more than 2 cups.
Coral says
Thanks for the yummy recipe. I made cake pop out of it, crumb the cake and add in chocolate syrup.
Marc Matsumoto says
Hi Coral, great idea! Glad to hear you enjoyed it!
detritus says
Ha ha, I ended up with the brownie you were initially trying for! I got interrupted in the middle of making this, and forgot to put in the oil. I ended up with a dense, rich, brownie that held together beautifully and stayed perfectly moist throughout an entire week, not drying out the way most brownies (and gluten-free baked goods in particular) normally do.
It was such a treat, and so easy to prepare, that I'm going to make it again this week, however this time I'm going to use coconut oil instead of butter, and actually remember to put it in!
h says
I'm so glad I found this recipe! I've been looking for a low sugar and/or gf cake for my daughter's 1st birthday "smash" cake. This sounds perfect! She already loves japanese sweet potatoes (it was one of her first foods), so I think this will be a hit! Will let you know how she likes it 🙂
Marc Matsumoto says
Hi Haems, one thing you'll want to do is to cut back on the amount of coco powder if you plan to serve it to your daughter. I'm one of those people that loves dark chocolate so I've added a ton, but it makes the cake slightly bitter, which a 1 year old palette may not enjoy. Chocolate also has caffeine in it so you may want to watch out for that as well. If you take out too much cocopowder though it's possible the cake won't set properly so you may want to consider substituting some rice flour or other gluten free flour for the cocopowder that you omit.
Marvin says
When you blend, is the sweet potato raw or cooked? I may have overread this? I do know cake recipes with precooked sweet potato, but I am not sure for this one. Helping a lot with your answere, I will immediately try it! Thanks!! : )
Marc Matsumoto says
Hi Marvin, the sweet potato goes in raw, the uncooked starch in it helps bind the cake together. This is also why it needs to be grated before it's added to the blender (otherwise you'll end up with chunks of sweet potato).
Monica says
You Sir, are a freakin genius! I made this last night because over the span of 3 weeks my CSA has given me 14 sweet potatoes and (as unbelievable as it is) I have gotten tired of sweet potato fries! So last night, there I was grating away on my hand grater and when it came time to combine all of the ingredients in the blender, it wouldn't budge, It felt too dry. And of course, I freaked out thinking, "great what is this monstrosity, never again!" So I put in an extra egg and it blended beautifully. The magic, though, was when I took it out of the oven. So springy and moist! I took it to a work potluck, and no one believed that this was gluten free and made with sweet potatoes. Thank you!
Jany says
Thank you! This was so good! I mixed everything inside my vitamix and then stirred in the baking powder at the end! The texture was great and it wasn't too sweet.