World's Smallest Chiffon Cake -- Purple Sweet Potato Piggies made in Mini Donut Pan

Elder kid requested for chiffon cakes to be made in the mini donut pan that he wanted me to buy a while ago. Experienced bakers will say that's a definite no-no since donut pans have non-stick coatings and I was afraid the black pan would heat up differently from my regular aluminum pans or glass bowls. Now that I am less afraid to make mistakes, I thought you might appreciate it if I did the experiment on your behalf ;). Here are my teeny purple sweet potato piggies baked in a mini donut pan!

It's pretty tough to take a photo with the donuts on my hand using a phone camera but I did it so you can see how teeny the chiffon cakes are with the signature hole in the middle :). The inside looks just like a miniaturized version of a chiffon cake!

Very soft and fluffy mini donut chiffon cake sitting in a Chinese soup spoon

The kids love it coated with a bit of white chocolate and the hole filled with purple sweet potato cream too!

I can just imagine doing a batch of these for class parties with different flavors and toppings!

I adapted the recipe from Vivian Pang as I prefer a smoother textured purple sweet potato cake for such tiny cakes. Some recipes call for potato chunks in the cake. I increased the amount of puree, oil and egg whites for my recipe. The quantity is really small as I was experimenting and didn't want to waste too much resources so feel free to double or triple the recipe if you have bigger donut pans or more than one pan.

Ingredients (makes 12 mini donut chiffons and one thin 6 x 6" flat layer cake):
1 egg yolk
5g caster sugar
28g fresh milk
25g purple sweet potato puree (Steam sweet potato until soft then mash. Pass through sieve to remove big lumps)
12g vegetable oil
1/4 tsp vanilla essence
20g cake flour
1/8 tsp baking powder
Pinch of salt

1.5 egg whites
20g caster sugar
1/10 tsp cream of tartar

Steps:
1. Prepare sweet potato puree.  I portioned mine into 25g packets and freeze any unused portions.

2. Preheat oven to 160 degrees Celsius. Place a tray that can fit the donut pan in it with some space around it into the oven. You will need to sit the donut pan in a water bath. I didn't do this so my donut chiffon rose and browned very fast. I prepared a tray to put hot water at bottom of oven instead which provided the steam but didn't insulate the donut pan. Boil some water. Line the 6" pan with baking sheet.
3. Whisk egg yolk and sugar until it turns pale. Whisk in oil, sweet potato puree, milk and vanilla essence in that order. Gradually whisk in sifted flour, salt and baking powder.

4. Prepare the meringue. In a clean metal bowl, beat egg whites until foamy. Add cream of tartar and beat until soft peaks form. Gradually add caster sugar until stiff peaks form.
5. Add 1/3 meringue into egg yolk batter and mix until no trace of egg white is seen. Quickly but gently fold in the remaining meringue in two additions. Tap the bowl a few times on the table to remove any trapped air. Spoon the batter into ungreased donut pan till about slightly more than 3/4 full and the 6" pan.
6. Place the donut pan into the tray in the oven and carefully pour boiling water into the tray using a jug or kettle. The water level doesn't have to be too high as baking time is short. Place the 6" pan in the oven. Turn the temperature down to 150 degrees Celsius after the oven door is closed and bake for 15 minutes.
7. Invert the donut pan immediately over cooling rack and unmould when cooled using a flexible spatula for the sides and a toothpick for the center.

8. Remove the flat layer cake from the pan as soon as possible and invert to cool with fresh piece of baking sheet covering it.
9. Use small round cutters or a jumbo straw to cut out the snouts of the piggies from the layer cake. Cut small slices for the ears. Melt some white compound chocolate the glue the parts onto the donut chiffons. You may melt some dark compound chocolate to draw in the eyes and nostrils but I was feeling lazy and just used food marker to draw them on.
10. Store the cakes in an airtight container.

I had plenty of leftover layer cake since I only made a total of 4 piggies (too lazy to make more :p). I topped and filled the rest with white chocolate and purple sweet potato cream (add some purple sweet potato puree to freshly whipped cream). Out of curiosity, I rolled it up and found it to be really soft and bendy!

Perfect candidate for a swiss roll! I rolled it up when it was completely cooled and left lying around for a while. Stay tuned for my next post for purple sweet potato swiss roll!

Overall quite satisfied with this experiment although baking conditions have to be tested again and fine-tuned. This type of mini cupcakes should be popular with kids as it is really soft, fluffy, handy to eat and can be topped or filled with the kids' favourite flavors. I will most likely be making this for my kids' children's day party in school unless some other better idea comes up.

With love,
Phay Shing