38. South Korean Sweet Potato Cake with Creamy Coconut Custard Frosting

This recipe was inspired by what I had left in my fridge. One lonely sweet potato. Upon returning from holiday to Amsterdam I needed a quick and exotic bake for my sister’s birthday. I wasn’t entirely sure that everyone would enjoy a South Korean sweet potato cake but hey, this is what you get when your little sister sets up an international baking blog challenge!

This was actually quite quick to make, the most time being spent peeling and dicing the sweet potato so it could be boiled and mashed into a gloriously orange mush.

Mushed Sweet Potato

I love sweet potatoes and have been eating them a LOT in my preparation for the Great North Run which is (gulp!!) next Sunday!! They promise many vitamins (A, C and B6), antioxidants AND they have anti inflammatory properties! Perfect for soothing those aching joints and muscles post running! ..So this cake is (almost) practically healthy!

Creamy butter and sugar

I started by creaming the butter and two types of sugar together with my handheld electric whisk for about 5 minutes until it became lighter and fluffy.

Then add one egg at a time and vanilla and keep on whisking

Then add the vanilla and eggs, one at a time,vanilla and keep on whisking until they’re incorporated completely. It take about 5 minutes to whisk the mixture up until it’s very light and fluffy.

Lots of fluffy eggs, sugar and butter

Then onto the dry stuff. In a separate bowl I mixed together the flour, baking powder, and salt.

Dry stuff, flour, baking powder and salt

Then to stir in the milk to the sweet potato along with the syrup (as I don’t keep maple syrup in my cupboard I substituted it for golden syrup 🙂

IN with the syrup!

Stir it all together until it’s a milky sweet potato soup

Sweet potato soup

Then to gently fold in a third of the flour to the fluffy eggs and butter mixture

Folding in the flour

And then fold in a third of the sweet potato soup

Folding in the sweet potato soup

And alternate folding in a third of the flour and a third of the soup until all the ingredients are incorporated creating an orange flecked liquid batter.

All in!

The original recipe was to make two 9 inch round cakes. But I wanted one big cake and I love my lazy cake pan (PushPan) and use it at every opportunity I get! It really speeds up the process as it’s really non stick and leak proof! AND my favourite bit! No lining required! No wasted paper and effort. Just a quick spritz with cake release et voila! One quick cake! I wish I could afford more of them.

Just baked. Look at that deep brown!

I used one 9 inch tin to cake all of the batter in a 180 degrees C (or 350 degree F)  oven for 40 to 50 minutes. Until it’s baked evenly, with a golden top. This cake shrank back beautifully from the sides of the tin too to tell me it was ready for eating. I made sure it was done by sticking a cocktail stick in it and it came out clean on my check.

I always leave a cake to cool in it’s pan for at least 15 minutes before turning it out to cool fully on the wire rack. I learnt this the hard way as I once took my Christmas cake out of the tin straight away and it fell into 3 massive chunks in my hands. I did shed a tear at this after waiting patiently for it by the oven for 5 hours. They definitely need a bit of cooling to hold their shape! (Luckily I managed to stick my cake back together with jam and a bit of marzipan to cover the cracks and no one knew the difference!)

Tester sweet potato cupcakes

I was worried that this cake might be a bit odd on our English palettes so I made some tester cupcakes alongside my large cake. I needn’t have worried! It was delicious! I has only meant to try the corner of one cupcake and 2 minutes later the whole thing has disappeared into my tummy. It’s quite a sweet and slightly savoury sponge. A bit like carrot cake but without the grated carrot texture. It’s also a lot more moist than carrot cake.

You could stop here as the recipe didn’t give any sort of filing or frosting and the cake is sweet enough to eat as a sponge in it’s own right. HOWEVER if like me you want to take things a step further I found an amazing recipe for Creamy Coconut Custard Frosting, which is very reminiscent of rice pudding with a whole can of evapourated milk but with dessicated coconut instead of rice. Delicious! And what I love even more about this recipe is it takes 15 minutes with no trace of icing sugar to be swept up from every corner of your kitchen afterwards! This is a great alternative to buttercream which my family aren’t a huge fan of.

Throw into a pan egg yolks,  evapourated milk, sugar and vanilla

Choosing my heaviest sauce pan I added the sugar, egg yolks and milk to it along with the vanilla and stirred it all together

Continue to stir over a medium heat for 12 minutes until it thickens

Once it reaches the ‘pudding’ stage (it’s as thick as pudding) take the pan off the heat, throw in the dessicated coconut and Bob’s your uncle you’ve made coconut custard!

Then it needs to be cooled completely before spreading it over your cake.

Creamy Coconut Custard Frosting

As Mary Berry ‘s sage advice is to include a little of what’s in your cake on your cake so I lovingly adorned the cake with slices of coconut too.

South Korean Sweet Potato Cake and Coconut Custard Frosting

I was very pleasantly surprised by this cake and the combination of coconut custard. This was my very first ever attempt at making custard too and given the opportunity (and a spoon) I could merrily eat the whole pan of it by itself. That would definitely warm you up on a winter’s night! It was so sweet and comforting. You probably couldn’t eat more than one slice as it is quite a dense cake but I’m always up for a challenge. Now I’m thinking about it again I wish I had another huge chunk to tuck into! I’m happy to report that my sister enjoyed it too!

Sweet Potato Cake and Coconut frosting a sideways glance

Things I used to make South Korean Sweet Potato Cake

  • 1 cup of soft butter
  • 2/3 cup white sugar
  • 2/3 cup brown sugar
  • 3 eggs
  • 1 teaspoon vanilla extract
  • 2 cups all-purpose flour
  • 1 cup cake flour
  • 1 tablespoon baking powder
  • 1 teaspoon kosher salt
  • 1 1/3 cups milk
  • 1 medium sweet potato, peeled, cubed, boiled, and mashed
  • 1/3 cup maple syrup (golden syrup)

15 min  Creamy Coconut Custard Frosting

Things I used to make Creamy Coconut Custard Frosting

  • 1 (13-ounce) can evaporated milk
  • 1 cup sugar
  • 1/2 cup butter or margarine
  • 3 egg yolks
  • 1 teaspoon vanilla extract
  • 1 1/2 cups flaked coconut