Japanese Sweet Potato Chiffon Cupcakes

I first encountered Japanese Sweet Potato Cake from Rei's blog. I had the honour to try out the cake when Rei brought them to a gathering. It was yummy!

Recently I saw a Japanese lady making it in a YouTube video. At the recent Hokkaido fair, I bought a similar sweet potato custard dessert. That was yummy too, but the sweet potato layer was far too sweet for me.

I decided to try to pair this Japanese Sweet Potato Cake with Chiffon cake in one of my recent Chiffon cake practice. The kids were getting bored with the conventional tube shaped Chiffon, so I thought changing it into cuppies may spice things up a little. The little trick worked. They were happily eating the cuppies without associating them with Chiffon cakes.



I've made the sweet potato cake to be sweeter to go well with my not-so-sweet Chiffon cake. If you like it to be not as sweet, use Rei's recipe.

Japanese Sweet Potato Chiffon Cupcakes

Ingredients

Sweet Potato mixture
550g Japanese Sweet Potatoes
30g butter, soften (suggest to reduce it to 20g)
50ml whipping cream (suggest to reduce it to 40ml)
20g sugar
1 egg yolk

Chiffon Cake layer
(A)
2 egg yolks
15g sugar
20g corn oil
30g milk
40g sweet potato mixture (see below)

(B)
2 egg whites
1/4 tsp cream of tartar
25g sugar

(C)
60g cake flour
3/4 tsp baking powder

Method
For the sweet potato mixture,
1. Steam the sweet potato over medium high heat for about 25-30 mins till cooked. Peel off the skin and mash them up. Net weight of mashed sweet potato is about 470g.
2. Add the remaining ingredients for the sweet potato mixture into the mashed sweet potatoes. I run the mixture in a blender for a smoother finishing. Reserve 40g of the mixture for the Chiffon cake.

For the Chiffon cake,
1. Sift cake flour together with baking powder.
2. Whisk the egg yolk with sugar till sugar dissolves.
3. Add the corn oil, milk and sweet potato mixture to the yolk mixture and mix well.
4. In a separate clean bowl, beat the egg white with cream of tartar till soft peak.
5. Add sugar in 2 separate additions and beat till just initial stage of stiff peak.
6. Gently fold 1/3 of the egg white into the yolk batter. Mix well. Fold in the remaining egg white in 2 additions. Mix well each time.



To assemble,
1. Fill 1/3 of small paper cup with the sweet potato mixture. Smoothen the mixture with a teaspoon.
2. Fill the remaining paper cup with the Chiffon batter till 80% full. Gently bang the paper cups on the table top to get rid of any trapped bubbles.
3. Bake the cupcakes in preheated oven at 170°C for about 25 mins.
Note: My oven usually takes longer to bake the cake. So you may need to reduce your baking time according to your oven.

This cupcake is ideally served with a spoon so that you can scoop the Chiffon and sweet potato layers together. Enjoy! :)