Sweet potato chiffon cake

Sweet potatoes - great for chips, roast dinners and barbecues. But who would've ever thought to use them in cakes?! I know....it sounds a bit weird but HEY - this is a gorgeous soft cake.

So I googled sweet potato chiffon cake and a range of recipes came up including purple sweet potatoes! I scavenged all around the supermarkets in the UK and had no luck so resorted to traditional orange sweet potatoes. It was depressing not having the chance to achieve the bright purple colours but it was great anyhow.

The texture was heavenly and although the cake didn't taste as potato-ey as I thought it would be, it was alright! It was a very light cake indeed. I originally badly failed on my first attempt due to a VERY - I repeat; VERY silly mistake. The recipe instructed for 100g of sweet potato. I looked on the bottom of the bag holding about 5 sweet potatoes and saw "90g" somewhere. So without weighing the potatoes, I dumped the whole bag in the mix. I thought it was quite light for such few potatoes but I was so excited about making this cake that I just didn't care. When my cake appeared to still be gooey and sticky after baking for over an hour, I realised something must have gone wrong. Later did I notice that the 90g was for one potato, not the whole bag. Great.

Here's the recipe. And make sure you weigh out the ingredients correctly :)

Sweet potato chiffon cake
makes one 7 inch diameter cake

A
3 egg yolks
20g brown sugar

50ml vegetable oil
100g sweet potato (boiled and mashed with 5 Tbsp of milk)
zest of 1 lemon

1/2 tsp baking powder
100g flour
1/2 tsp salt

B
3 egg whites
40g caster sugar
1/4 tsp cream of tartar

1. Peel and cut sweet potato into chunks. Boil until cooked and mash with milk. Leave to cool.
2. Sieve flour, baking powder and salt together, set aside.
3. Separate egg yolks/whites.
4. Mix together egg yolks, oil, brown sugar and lemon zest.
5. Whisk the flour mixture and oil/egg yolk mixture until fully incorporated. Add in sweet potato and mix well.

6. In a clean, dry mixing bowl, beat egg whites, cream of tartar and sugar with an electric mixer stiff peaks form.
7. Add the beaten egg white into the egg yolk batter in 3 separate additions, each time folding gently with a spatula until just blended.

8. Pour batter into a 7 inch tube pan (do not grease the pan). Tap the pan lightly on a table top to get rid of any trapped air bubbles in the batter. 8. Bake in preheated oven at 170 C for 45 minutes or until the cake surface turns golden brown, and a skewer inserted into the centre comes out clean.

9. Remove from the oven and invert the pan immediately. Let cool completely before unmold. To remove the cake from the pan, run a thin-bladed knife around the inside of the pan and the centre core. Release the cake and run the knife along the base of the pan to remove the cake.