Rainbow Cake

1. Preheat the oven to 180 degrees.
2. Cut out 6 circles ( 12 cm diameter) from baking paper to line the cake tin for each layer.
3. Sift the flour in a bowl, mix the salt and baking powder.
4. In a freestanding electric mixer mix the butter and sugar until pale and fluffy then add the eggs one by one.
5. Add the vanilla extract and then the flour. Mix until well incorporated.
6. On a kitchen scale weigh the mixture and divide into 6 bowls.Now it's time for coloring: make sure you mix the food coloring very well otherwise you will get marbled sponge.
7. Pour the mixture in the prepared cake tin ( lined with baking parchment) and bake them in the preheated oven one by-one for 20 mins. As soon as the are ready transfer them on a cooling rack.
8. For the filling mix the cream cheese and icing sugar then add the butter. Put the cream in the fridge for half an hour, it will be much easier to work with it.
9. Now it's time to assemble the cake: you will need the same cake tin you were baking the layers in. As the cake will be quite high it's good idea to put a hard cardboard paper around the cake tin.It will hold the cake in position and you can avoid leaning tower of Pisa-effect. Also try not to put too much frosting between the layers, just enough to stick them. As soon as you built the tower try to squeeze in your fridge for an hour. you may have to remove a shelf from the fridge.
10. After an hour remove the paper around the cake and cover the side of the cake with the remaining frosting. You can decorate as you like but I think it's better to leave it white so it will make a big surprise when you cut the cake.:)