Matcha Charcoal Ogura

Meeting up my old times buddies today, so I decided to bake them a nice ogura :)
Modified this from my first successful Ogura recipe :)

Ingredients
(A)
5 egg yolks
1 whole egg
1/4 tsp salt
40g canola oil
90g milk
90g plain flour

(B)
5egg whites
100g castor sugar
1/4 tsp cream of tartar

(C)

2tsp matcha powder

2tsp charcoal powder

Method

1. Preaheat oven at 160C
2. Lined the bottom of a 7; square tine or 8" round tin. *will be using waterbath method , so do not use a tin with removable base!
   For (A): 
3. Beat egg yolks, whole egg, salt, oil & milk with hand whisk, until fluffy.
4. Sieve in flour then mix it up until well combined.
   For (B):
5. Beat egg white, cream of tartar & castor sugar until firm peaks form.
6. Using a hand whisk, mix 1/3 of (B) mixture at a time, into mixture (A).
7. Switch to a spatula to lift batter from bottom to fold.  Be sure the mixture is well combined & smooth.
8. Spilt batter into 2 portions.
9. Sieve and fold in matcha powder into 1 portion.
10. Sieve and fold in charcoal piwder into 1 portion.
11. Spoon in the batter from each portion spontaneously into the baking tin. Then tap the tin on the table top few times to release air bubbles.
12. Put the baking pan into another larger pan, then fill the latter up with hot water (1/3 of the tin with batter).
13. Send to bake at 150C for 70min.
14. Once baked, remove from oven and invert the cake immediately on a cooling rack to cool.  If you want a soft surface, invert on a non stick frying pan.