Preheat oven to 160°C / 350°F/ Gas 4
Line 5 round 7-8inch baking tins with greaseproof paper. If you don’t have enough tins you can clean and reline the tins after use and bake in batches.
Beat the butter and sugar together until light and fluffy in texture.
Add the eggs one at a time, including a spoon of flour with each. Ensure that both the egg and flour are mixed in well before adding the next.
Once you have added all of the eggs, fold in the last of the flour. Don’t beat the flour in as this creates bubbles in the mixture.
Divide the cake mixture evenly between the bowls.
Add a small amount of the red gel paste to the first bowl and mix well.
Add a different colour to each bowl
Return to the first bowl, beat the mixture again and add to a cake tin. Repeat this process for each of the coloured bowls.
Bake for approximately 20 minutes until they are springy to the touch.
Leave to cool for five minutes before removing carefully from the tins.
Allow to cool completely before icing.
While cooling, prepare the icing.
Beat the butter for 5-8 minutes using a food mixer. It should be really creamy. Sieve in the icing sugar, mix for another five minutes. Add the milk and vanilla extract and mix for one last time.
Use the first cake for the base; if the cakes are not level you can use a serrated knife to even them out. Cover the top of the cake with a thin layer of icing and stack the next layer on top. Repeat the process until all layers are covered.
Decorate with sprinkles or whatever your birthday prince or princess wil love!