Rainbow cake

Another check on my to-do list ~ Rainbow cake! Looking at the cake itself makes one so happy lol.

I'm using my usual vanilla sponge cake recipe to make a 7-layers 4.5" round cake. I'm also using my now-favourite cream cheese frosting. Both the sponge cake and frosting turned out very good!

My frosting skills is still quite bad, so I've to create some "designs" to hide the flaws.

Vanilla Sponge Cake

Ingredients/ Method:
(A)
150g cake flour/superfine flour
1/2 tsp (2g) baking powder
1/4 tsp (1g) salt
10g milk powder

(B)
60g cooking oil
50g water
4 (75g) yolks
80g castor sugar
1 tsp vanilla extract

(C)
4 (150g) whites
90g castor sugar (original 100g)
1/4 tsp (1g) cream of tartar

(D)
Colour gel

1. Sift ingredients (A) and put it aside
2. Whisk yolks and sugar till it turns lemon color
3. Add oil, water and vanilla and mix till well blended
4. Add ingredients (A) and mix it slowly till it forms a smooth batter
5. Whisk (C) till stiff
6. Fold in 1/3 of egg white mixture into egg yolk mixture and gently stir, then fold in the remaining egg white mixture and mix well gently
7. Divide batter equally into 7 portions and into individual small bowls. (I got about 90g for each portion, but I would reduce it to 60-70g the next time.)
8. Add colour gels into batter and mix well gently, and not to deflate too much air bubbles.
9. Pour batter into lined cake tin. (I used disposable aluminum foil-type 4.5" round tin as I don't have so many cake pans.)
10. Bake in a preheated oven 180C for 10-12 mins or when skewer comes out clean when inserted to the centre of cake.
11. Removed from oven and let cake cool in pan for 5 mins on wire rack.
12. Remove cake from pan and let it cool completely on wire rack.

Notes:

1. If using the same size 4.5" round tin and 7 layers, just need to prepare 2/3rd of this recipe. Alternatively, you can bake the balance 1/3rd batter as vanilla cupcakes.
2. As my oven can only bake 4 small tins at a time, I mix the egg yolk mixture and egg white in 2 batches.
3. I used toothpick when adding and mixing colours to the batter, and using a small spatula to give a last few folds to ensure colours are evenly mixed.
4. Insert straws to hold the cake, especially when this cake base is small and pretty tall. 

Cream cheese frosting
250g cream cheese
170g unsalted butter, softened
70g icing sugar, sieved
1 tsp vanilla extract

1. Using an electric mixer on medium-high speed, beat butter and cream cheese until fluffy, about 2 to 3 minutes.
2. Reduce speed to low. Add sugar in three batches, then add vanilla and mix till smooth and combined, scraping down sides of bowl as needed. (If not using immediately, frosting can be refrigerated up to 3 days in airtight container. Before using, bring to room temperature and beat on low speed until smooth again.)