Azuki and coconut milk chiffon

I still have a lot of cake flour which I try to use up before summer comes. Decided to use my frozen tsubuan which I made quite some back as well. Based on the density of the tsubuan, decided to adapt the recipe for chocolate milk and cocoa chips because this recipe has more flour which will give it the density to 'hold' up the tsubuan. 

http://thedomesticgoddesswannabe.com/2016/02/chocolate-milk-chiffon-cake-with-chocolate-chips/

I substituted the milk for coconut milk and choc chips for tsubuan and some other changes e.g. sugar and milk volume. Didn't turn out too bad. Surprisingly seems a bit undercooked compared to when I usually bake this which comes out really brown. Really moist though. At first I thought the temp may be too high (170 deg C usually is) but as you can see, the top has already cracked.

Ingredients

7 eggs, separated

210 ml coconut milk

120 ml oil

35 (for yolks) + 135g (for whites) sugar

225g cake flour

¾ tsp baking powder

½ tsp salt

140g tsubuan or koshian

Method

1) Add the 35g of sugar to the yolks and beat till the sugar has mostly dissolved. 

2) Add the oil and beat until paler in colour. 

3) Add in the coconut milk and salt. Whisk until combined.

4) In 2 batches, sift in the cake flour and baking powder and fold using a whisk. Try not to over beat or you will develop gluten. Set aside.

5) In a very clean bowl (no oil, water, or detergent), beat the egg whites on low speed until foamy and opaque. Add sugar in 3 batches. After all the sugar has been added, turn up the speed to max and beat until stiff peaks.

6) Add the meringue to the yolk mixture in 3 batches. The first batch: incorporate till no streaks remain. You don't have to be too gentle. The second batch: This time, fold in gently so as not to knock out the air. The third batch: This time, return the yolk mixture to the left over third of meringue. Very gently fold in with a whisk (my preferred) or spatula until just combined.

7) In the ungreased 26 to 26" cake tin, pour in ⅓ of the mixture. Top with ½ of the tsubuan, trying to distribute evenly. Top with the next ⅓ of the cake mixture and another ½ of the tsubuan. Finally, cover with the remaining batter.

8) Using a spatula, run around batter in a zig zag manner and pay attention to the edges of the tin and around the centre funnel. This will disperse the bigger air bubbles and also swirl the tsubuan. (The original recipe recommends dropping the cake tin on the counter to dispel more air bubbles but I don't do this if the recipe has a very dense filling which will tend to sink to the bottom anyway as you can see from the picture)

9) Bake at 170 deg C for 65 minutes. Tent in the last 20 minutes or adjust to 165 deg C for up to 70 minutes, checking at 65 mins. Remove and immediately invert and allow to cool completely in the tin.

10) Unmould by running a knife or spatula around the edges and invert onto a plate. The bottom should be the top of the cake because that's where it's flattest.

Recipe feedback

The cake came out very slightly undercooked inside although the outside was quite brown. I have adjusted the recipe to bring down the temp from 170 to 165 deg C and to increase from 65 to 70 minutes. Alternatively, to tent the cake.