A delicious cake for the autumn season, this sweet potato cake with brown butter frosting will surprise you with its deep flavours. An intense brown butter frosting fills and tops a cake made with roasted sweet potato, brown butter and coarsely ground cardamom for an explosion of flavours! A great alternative to carrot cake with cream cheese frosting.
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.
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.
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.
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.
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.
This recipe is meant to be baked in a 16-cm round cake pan, and yields about 4-6 portions. If catering to a larger party, double the cake batter ingredients to fill a standard 22-24 cm cake pan.
The frosting quantity in this recipe is enough to fill and top a 16-cm cake. If making a larger cake, the frosting will only be enough for a top layer; double the frosting quantities if you wish to have the frosting both on the top and in between cake layers.