Purple sweet potato chiffon cake
DATE: 17/10/17
RECIPE: http://www.bearnakedfood.com/2016/07/06/purple-sweet-potato-chiffon-cake/
120g boiled purple sweet potato
3 tbsp milk -> 1/3 scoop powder + water to make 45ml
3 egg yolks
30 g sugar -> 18g
50ml vegetable oil
3 tbsp water -> 45ml
85g cake flour -> 70 AP + 15 corn starch
4 egg whites
60 g sugar -> 30g
½ tsp cream of tartar (by eye)
1. boil sweet potato (takes like 30 min), cool, peel, weigh, break into smaller pieces with fork, add milk and mash.
2. separate eggs. measure flour & starch, transfer to soup bowl, mix and fluff very thoroughly with fork. measure 48g sugar and divide by eye.
3. add 20g sugar to yolks, mix till pale and fluffy. add water, oil, mix till combined. add sweet potato paste, mix till combined. add flour, fold until smooth. (omg smells like actual potato. but my sweet potato is purple-grey so the batter is like grey-brown lol)
7. whisk egg whites & cream of tartar till foamy, gradually add sugar and whisk till just stiff peaks.
8. fold 1/3 meringue into batter. pour batter back into rest of meringue. fold till combined.
9. line base of pan but not sides. pour batter into pan (batter is like 1cm from rim of pan). tap on counter to release bubbles. bake in oven preheated to 170C for 15 min. turn down to 140C and bake for another 20 min.
10. remove from oven, immediately turn upside down (prop up with like a book on each side).
prep & washup took 1 hr 15 min.
in oven - it’s very pale and cute. mini cracks around the sides started at about 15 min. covered with foil when 3 min left. gave it an extra 3 min (just because my usual bake times are like 50-60 minutes so i didn’t believe 35 would do it), so 38 min altogether.
instantly turned it upside down but this time actually got 2 tins to prop up each side so the cake was hanging.  15 min later it falls out onto the table lol so i just leave it. when it’s cool i peel off the paper and turn it right side up and the top stuck to the table :’( it would have been so pretty otherwise. but F**KKKK the bits stuck on the table tasted SO GOOD. like potatoey and moist and just amazing in a subtle way.
sliced cake when cool - THE MOISTEST CHIFFON CAKE I HAVE MADE - 38 MIN IS PERFECT. moist in middle and sides (the bits stuck on side of tin were moist and not dry) and so fluffy, no dense layer. defs cool the same way from now on … but maybe find lower props so it doesn’t fall as far if it falls. if my tin had a removable base i could stop lining the bottom but it doesn’t so if i don’t line it idk how i’d get the cake out.
flavour of the cake is subtle and potatoey (it’s more potatoey than sweet potatoey … potato-like and sweet, rather than sweet-potato-like). subtle like taro, subtle like chestnut. fark i love subtle flavours *____* this is so good. i reckon the bake-at-high-temp-and-then-lower is a good technique because my most-successful first choc sponge was done like that (except that was low temp and then high temp, and bake time was 50 min - which was why i was iffy about 35 min).
cut it into 19 slices - 66kcal per slice
use lower props for cooling so cake doesn’t fall as far if it falls