- Rainbow Sponge Cake (3 sheets):
1. Preheat oven at 170°C/340°F. Grease and line parchment paper on a three 7-inch round pizza pans.
2. Separate the eggs (yolk and white).
3. In a large bowl, add the egg yolks, sugar. Mix well until sugar almost dissolved. Add oil, milk, vanilla extract and salt. Mix until well combined.
4. Sift the flour into the mixture in 3 batches. Whisk in a circular motion until the flour disappear.
5. In another bowl of egg white, add cream of tartar. Mix until bubbly. Gradually add in the sugar. Continue mixing until stiff peaks formed.
6. Add the egg white mixture into the batter in few batches. Use a whisk and mix gently in a circular motion. Do not over mix. Mix just until it is well combined.
7. Pour the batter into the prepared pan. Tap the pans few times on the table.
9. Bake in preheated oven at 170°C/340°F for 30 min and 140°C/285°F for 35 min.
10. Repeat the same process for another 3 sheet cakes (the other 3 colors)

 

- Swiss Meringue Buttercream:

1. Prepare a double boiler.

2. In a bowl, add egg whites and sugar in a heat safe bowl. Place the bowl on top of the prepared double boiler.

3. Continuously whisk the mixture while cooking. Cook over a low heat. Be cautious that high heat will overcook the eggs. This process will take at least 5 min or so. Cook until it reaches temperature between 65-70°C. This is to ensure safety consumption. Once it reaches the temperature, remove the bowl from the boiler.

4. Start whisking on low. The mixture will get a little frothy. Increase speed to high. The bowl is still hot, and by increasing the mixing speed, this will eventually reduce the temperature. Mix until the bowl is completely cool. The meringue will become sticky and stringy, something like a fluff. Make sure the mixture is completely cool (before adding the butter), you’ll know by touching the bowl.

5. Add the butter cubes, add one by one. Don’t get panick when the mixture gets a little curdled and breaking down. As you add the butter towards the end, the mixture’s consistency will come back together. Your mixer paddle will be able to hold the cream, and that’s good to go.

6. Add in the vanilla extract, and mix until combined.

 

- Assemble the cake.

1. Brush some sugar syrup on the cake.

2. Add the buttercream.

3. Chill the cake while preparing for the color frosting.

 

- Rainbow color frosting preps

1. For the remaining buttercream, divide into six, however reserved a little more for the red as you’ll need more red to cover the top of the cake.

2. Pipe strips by strips of the colors onto the side of the cake.

 

- Deco

1. Piping some dollops using whipping cream. You can also use more buttercream if you desire.

 

Chill the cake before cutting.