Vanilla and Choc Chips Chiffon Cake

This is the third time I baked vanilla choc chips chiffon [original recipe from Peng's Kitchen].  There are some slight modifications to the ingredients and method.

The chiffon cake is soft, light and moist.

Ingredients for Egg Yolk Mixture

120 gm cake flour - sifted
3 tbsp castor sugar
1/2 tsp salt
4 egg yolks

4 tbsp oil [60 ml]

60 ml milk
1 tsp vanilla essence 
60 gm chocolate chips

• In a mixing bowl, put in sifted cake flour, sugar and salt.  Make a well in the centre, pour in egg yolks, oil, vanilla essence and milk.  Using a paddle hook, whisk ingredients  [on medium to high speed] until egg yolk mixture is creamy and thick.  Fold in half of the chocolate chips. Set aside while you whisk the egg white.  Preheat oven at 180 degrees C.

Ingredients for Egg White Mixture

3 egg whites [can use 4 egg whites]

1/4 tsp cream of tartar

3 tbsp sugar 
some cocoa powder [optional]

• Whisk egg white until frothy, add in cream of tartar, continue whisking, when foamy, gradually add in sugar.  Whisk until soft to stiff peaks formed [I used speed 5].
• Fold in 1/3 portion of meringue into egg yolk mixture till well combined.  Then fold mixture into balance meringue till well incorporated.   Add in remaining chocolate chips.  Fold lightly.
• Pour 1/3 of batter into 7" chiffon pan, sieve some cocoa powder over batter [this is to create some line pattern in the cake] top with another layer of batter then sieve on top another layer of cocoa powder.  Top with remaining batter.  
• Smooth the surface with a spatula.  Tap a few times on tabletop to release air bubbles.   Bake in preheated oven at 180 degrees for 30-35 minutes. 
• Invert pan immediately after baking to cool cake before removing from pan.