Sift both flours into a bowl and set aside. Add the ingredients for brushing into a bowl and heat in microwave until the butter melts. Mix well and set aside.
Add butter and sugar into another bowl. Whisk until pale and fluffy, around 5 minutes. Then add in oil, condensed milk and vanilla extract. Mix well.
Add egg yolk 1 by 1, mixing well after each addition. Add in flour mixture in 2 additions, mixing well after each addition. Don't over mix. Set aside.
In another bowl, add in egg whites and whisk until foamy. Then add in sugar and cream of tartar. Whisk until firm peaks or until the mixture doesn't fall when you flip the bowl.
Add half of meringue into the flour mixture and using a spatula, gently fold everything together until well combined. Add the rest of the meringue and continue folding to combine. Set aside.
The Coloured Batter
Weight 10.5 oz (300 gr) base batter each into 2 different bowls.
Take 2 tbsp of batter from 1 bowl and mix it with red food colouring. Then add the coloured mixture back into the bowl and fold everything together until well mixed.
Do the same with the other bowl using green food colouring. Set aside.
Baking and Layering
Preheat oven at 340ºF (170ºC) using grill function. Line the base of a 9 inch (23 cm) square pan. Line the base of a 13x9 inch (33x23 cm) rectangle pan. Don't grease the sides.
Put 3.5 oz (100 gr) of plain batter into the 9 inch (23 cm) pan and spread it evenly. Bake for 5 minutes or until fully cooked. Rotate the pan during half baking time.
Remove pan from the oven. Immediately smooth out the surface by lightly pressing it using the bottom of a glass. Then brush the surface with butter and condensed milk mixture.
Now add 3.5 oz (100 gr) of red batter and repeat the same process. Alternate the colours with plain batter in between. You will get 2 layers of red, 2 layers of green and 5 layers of base in between them.
After baking the final layer, leave the pan to cool for 10 minutes. Then run a knife on the sides of the pan to loosen the cake. Flip the cake onto a smooth tray with a baking sheet and set aside to cool completely.
Note: Use smooth tray so that there are no lines marked on the surface of the cake.
Add 8.8 oz (250 gr) of base batter into 13x9 inch (33x23 cm) and spread evenly. Bake for 5 minutes of until fully cooked. Rotate during half baking time.
Remove from the oven and leave for 2 minutes. Then flip it onto a smooth tray with a baking sheet. Leave to cool completely. Wrap with cling film to prevent it getting dry while not using.
Trim off the edges for the layer cake. Measure the height of the cake. Slice the cake into strips using the height measurement as the width, resulting a perfect square long strips. Choose the best 4 strips.
Arrange the 4 strips so that the designs are contrast to each other. See the video for guidance. Brush the sides of the strips that will touch each other with some condensed milk and attach them together into a log. Wrap tightly with cling film and chill in the fridge for 30 minutes so that it holds its shape better.
Trim off 1 end of the rectangle cake. Place the log on top of the cake at the trimmed edge. Gently roll the log, covering it all sides with the cake. Trim off the balance of the cake.
Wrap the log tightly with cling film and chill in the fridge for minimum 2 hours. Before slicing, trim off both ends to get that perfect and neat look. Slice and serve. Enjoy!
1. Don't over bake your layers. Bake them just so that they're cooked.
2. Oven temperature varies between ovens so keep an eye on your cake.
3. Wrap the wrapper cake with cling film to avoid it getting dry while waiting for the layer cake to cool.
4. You will have balance of cake strips. Incorporate them in your cake design if you want or save them as cook treats ;).