On the lookout for the best fall cake recipe? Look no further. This sweet potato cake with brown butter frosting has everything you need for a cozy sweet pause with a cup of tea on an autumn afternoon. Roasted sweet potato mash is one of the key ingredients of the cake, together with coarsely ground cardamom. The frosting has the unexpected flavour of browned butter, and if you ask me, there is nothing that could pair better with the sweet potato cardamom cake base. Your family and friends will love it at Thanksgiving!
Brown butter frosting on brown butter cake
If you haven’t yet jumped on the brown butter bandwagon, you should. I have been a huge fan of this delicious twist to regular butter I almost can’t live without it. Especially since I moved to Sweden, where butter is generally salted. Salted brown butter is everything, my friends. Especially in cakes.
Yes, you always need that pinch of salt in every cake you make, right? So why not just add salted butter? Going for a little bolder flavour? Browned salted butter is what you need in your life. And most definitely you need it in your cakes. Wanna have a test? Go for this sweet potato cake, which has brown butter both in the cake batter and in the frosting. The perfect cake to whip up this upcoming Thanksgiving!
Love layer cakes? Try this small tiramisù cake!
Sweet potato cake with brown butter frosting recipe
This sweet potato cake with brown butter is fairly easy to make, but requires some cooling times here and there. To save on time, I recommend following these steps. Detailed instructions are described below throughout the post.
- First, take care of the brown butter, to give it time to cool as well as harden;
- While the butter is cooking, and before it reaches boiling temperature and needs supervision, peel and chop the sweet potato. Then place in the oven to bake;
- When both the sweet potato mash and brown butter have cooled to room temperature, make the cake batter;
- While the cake is baking, take care of the frosting.
You can use the fridge or freezer to speed up the cooling times, but keep in mind that these times may vary, so allow some extra time to make sure you’re not using ingredients that are too hot just because you’re in a rush. Make this cake when you have time to devote for it. Quantities are fairly small, and so is the cake (we’re using a 16-cm pan) so it should not take very long overall, anyway.
Step 1: How to make browned salted butter
First of all, check the amount of salt in your salted butter. In Sweden there are three varieties of butter one can commonly find in supermarkets. The regular butter is generally salted and contains about 1-1,2 g of salt per 100 g. There is also an “extra salted” version that contains 1,8-2 g of salt per 100 g. Definitely less common and not so easy to find in smaller shops is unsalted butter. The butter I used in this recipe is the regular salted butter with a salt content of 1,2%.
Since in this sweet potato cake recipe we’re using brown butter both in the cake batter and the frosting, it is a good idea to start making a batch of brown butter that will serve the whole recipe. Add 175 g of salted butter to a saucepan and set it on medium-high heat. Let the butter melt completely. When it reaches boiling temperature, the surface will get frothy and the water naturally contained in the butter will start to evaporate. From this moment it is wise to keep an eye on the butter and stir it to prevent the proteins from sticking to the bottom of the pan and burning.
Related: sweet potato gnocchi with brown butter.
Keep stirring (or whisking, I actually prefer using a whisk for this procedure) until you see that the white particles floating in the fat (the milk proteins) on the bottom of the pan have started to turn brown. You can keep track of the temperature with a food thermometer: your brown butter is ready when it reaches 125°C (257°F). When done, immediately transfer the brown butter into a bowl to stop the cooking process, as letting it sit in the hot pan could eventually make it burn. If you don’t have a thermometer, you can tell it’s ready when the milk proteins have turned light brown from white.
Step 2: Preparing the roasted sweet potato
The other star of the show in this fabulous sweet potato cake with brown butter is obviously the sweet potato. In this recipe we’re using it roasted, as opposed to boiled. Roasting brings out all the sweetness of the sweet potato and perfectly complements the “burnt” tones of the brown butter. We only need 150 g of roasted sweet potato mash in the cake, but if using a large sweet potato I’d recommend to go ahead and roast it all. Leftovers can be frozen for future use or just enjoyed as side dish later in the day!
Peel and chop the sweet potato. Rub some olive oil over its surface and place the bits on an oven tray lined with baking paper. Bake in the oven at 200°C for about 20 minutes or until cooked through. Baking time may vary depending on sweet potato bits size. Let the roasted sweet potato cool to room temperature, then blend until smooth with a hand blender. Separate a half cup (150 g) to use immediately in the cake.
Related: sweet potato and goat cheese quiche.
Step 3: Make the sweet potato cake batter
When both the roasted sweet potato mash and the brown butter have cooled to room temperature, it is time to make the sweet potato cake batter. Combine the eggs and dark muscovado sugar and beat at medium speed for about 2 minutes, or until the mixture is smooth. Muscovado sugar can be lumpy, so make sure to beat the sugar and egg well. Lower the mixer speed and incorporate the sweet potato mash. Then add the liquid brown butter and mix that in. Set the mixer aside, take a silicone spatula and stir in the milk.
Combine the flour and baking powder and sift this powdery mixture into the cake batter. Gently fold in with the spatula. Open the cardamom pods to release the seeds and coarsely grind the seeds in a pestle. Add the cardamom to the cake and fold it in. Transfer the cake batter to a springform pan lined with baking paper and bake in the preheated oven for 45-50 minutes or until a toothpick inserted in the centre comes out clean.
This is a small cake that serves 4-6 people, baked in a 16-cm round cake pan. If you wish to make a larger cake, double up the batter ingredients. If you wish to both fill and top a larger cake with frosting, double the frosting ingredients; otherwise the frosting quantity in this recipe will be enough to just frost the top of the cake, carrot cake style.
Step 4: Make the brown butter frosting
The second batch of brown butter should have hardened. Ideally we want to whip it at room temperature, so do not leave it in the fridge overnight if making this recipe over two days. It is okay to harden it in the fridge, though, if you are going to whip it as soon as it hardens.
Beat the hardened brown butter at high speed for about 3 minutes, it should get paler and glossy. Add the cream cheese and powdered sugar and start the mixer again, this time at low speed. Mix until incorporated. You could add some vanilla to the frosting, or even some extra cardamom, but keeping things simple will work just fine and no other flavour will overwhelm the brown butter tones.
Step 5: Assemble the cake and serve
The amount of frosting we get in this recipe is enough for two layers, so you can cut your cake in half and fill it with half of the frosting, then spread the rest over the top of the cake. Alternatively, you can also go for a classic “carrot cake look”, which is to say a taller cake with the frosting only on the top. If doing so, the frosting layer will be much thicker. I personally think that having a layer of frosting in the middle helps get the combination of flavours at every bite. I also like that it keeps even more moisture in the cake.
This cake will last in the fridge for 3-4 days, but will dry up as the time passes. Since this is a small cake, I’d recommend making it fresh and serving it directly, or after just a few hours of chilling. Serving so few people, it’s unlikely there will be any leftovers, really. A delicious alternative to other classics, something between a sweet potato pie and a carrot cake, this sweet potato cake with brown butter might become your new Thanksgiving favourite!
Post updated September 2020.
Sweet potato cake with brown butter frosting
- 175 gr butter
- 150 gr roasted sweet potato mash (see instructions below)
- 2 eggs
- 100 gr muscovado sugar
- 50 ml milk
- 150 gr flour
- 1 tsp baking powder
- 1 tsp coarsely ground cardamom
- 200 g cream cheese
- 80 g powdered sugar
Step 1: Roast the sweet potato and mash
- Peel and chop the sweet potato. Lightly rub some olive oil over the pieces and lay over an oven tray lined with baking paper. Bake for about 20 minutes at 200°C, or until the sweet potato feels cooked through. When done, let cool to room temperature and blend with a hand blender until smooth. In this recipe we are only using 150 g of sweet potato mash, which equals 1/2 cup. Unless using a fairly small sweet potato, I recommend going ahead and roasting a whole potato, then taking the amount needed for the recipe. Leftovers can be stored in the freezer for future use or enjoyed as side dish to whatever meal you're having after making this cake.
Step 2: Brown the butter
- Add 175 g of salted butter to a saucepan and set on medium-high heat. Let the butter melt and reach boiling temperature. Keep cooking it until the white particles in the fat (the milk proteins) turn light brown from white. If using a thermometer, this happens at 125°C. Stir the cooking butter from time to time to prevent the proteins from sticking to the bottom and burning. When the brown butter is ready, immediately transfer it to another container to stop the cooking and prevent it from burning.
- Separate 50 g in one container and 90 g in another. The 50 g should cool to room temperature and stay liquid. The 90 g should harden, so you can keep it inthe fridge until you're done with the next steps.
Step 3: Make the sweet potato cake
- Combine the eggs and sugar and beat at medium speed for 2-3 minutes. Muscovado sugar can get clumpy, so make sure to get a smooth texture when beating. Lower the speed and add 150 g of sweet potato mash, then 50 g of liquid brown butter. Both need to be at room temperature.
- Set the mixer aside and stir in the milk. Combine the flour and baking powder and sift mixture into cake batter, folding it in gently. Lastly, fold in the coarsely ground cardamom.
- Transfer batter to a 16 cm springform pan lined with baking paper and bake in the preheated oven at 180°C for 45-50 minutes, or until a toothpick inserted in the centre comes out clean.
Step 4: Make the frosting
- Whip the hardened brown butter (90 g) at high speed for about 3 minutes. Add cream cheese and sugar and whip at low speed until incorporated. Chill until the cake has cooled and can be frosted.
Step 5: Frost the cake
- When the cake has cooled to room temperature, cut it in half to create two layers. Spread half of the brown butter frosting over the bottom layer, cover with top layer and spread remaining of the frosting over the top. Keep chilled until serving time.