How to create a... Rainbow Zebra Cake!
This on-trend rainbow zebra cake by Britt Box has a striking black and white pattern on the outside with a psychedelic surprise inside, taking the classic zebra print to another level! 
For this cake, I’ve used an 18cm (7in) round tin with enough mix for a 20cm (8in) tin. I find that once you separate the mixture into six bowls to make the rainbow colours and transfer them back to the tin, you sometimes lose a little. To compensate for this, I made more to begin with.
You will need:
My 20cm (8in) cake recipe (for an 18cm (7 in) tin:
- 300g (10½oz) self-raising flour
- 300g (10½oz) caster sugar
- 300g (10½oz) Stork/unsalted butter
- 85g (3oz) plain flour
- 5 free-range eggs
- 1½ tsp vanilla extract
- Sugarflair concentrated colours: Red Extra, Tangerine, Melon, Party Green, Aqua, Grape Violet
For the buttercream
- 250g (9oz) unsalted butter
- 500g (1lb 1oz) icing sugar
- 1 tsp vanilla extract
- Sugarflair concentrated colour: Grape Violet (optional)
For the zebra pattern
- sugarpaste: black, white
Equipment
- 6 bowls
- cake leveller
- pizza wheel cutter
- plastic smoothers
- cranked palette knife
- 23cm (9in) cake board
- edible glue
1. Cream together the Stork/butter and caster sugar. Add the eggs and mix well. Add both the plain and self-raising flours and mix, then add the vanilla and mix again. 2. Separate the cake mixture into as many bowls as you’d like for your different colours; I’ve used six colours. Separate them using a large ice cream scoop, then take out one scoop at a time in each bowl to make it even – I found each bowl had three large scoops in.
Apply and mix the colour
3. Next, you’ll need to colour the mixture – I find that concentrated gel colours are best and you can pick them up easily online or in your local cake store. Water-based colours aren’t great for this as they aren’t bake stable and the colour fades a lot, plus you would have to use much more of the product, which can taint the taste of the cake and affect the consistency. 4. Use a cocktail stick to add a small amount of each colour to your batter, then stir with a spoon. Remember, you can always add more colour, but you can’t take it away once it’s mixed in; a little goes a long way! 
Bake the cake
5. Once the colours are mixed, spoon them into a lined 18cm (7in) tin, one at a time, to create a ripple effect. Once each colour is in the tin, spread it around a little using the back of the spoon to make room for the other colours – I used half of the bowl of purple, then half of the bowl of blue, followed by green, yellow, orange and red. I topped it in the same pattern with the following half of the mixture to make a really psychedelic cake! 6. Bake at 140°C/Gas Mark 1 for 1 hour 45 minutes, or until a skewer comes out clean. Once baked, turn out onto a sheet of greaseproof paper and leave to cool. Wrap well in clingfilm and leave to settle overnight. 
7. I wanted a nice contrasting filling to go with the bright colours so I made a pale vanilla buttercream. To do this, cream the unsalted butter on a high speed for 5-7 minutes, or until it has gone from a yellow to a pale, aerated shade. Add the icing sugar and vanilla extract. Mix well until you have a nice, soft buttercream. If you want it even lighter, bordering on white, add a TINY amount of Sugarflair Grape Violet. I mean a teeny tiny amount – too much and you’ll have purple buttercream, but just the right amount will neutralise the yellow, creating a white colour.
Cut and fill the cake
8. Unwrap the rainbow cake and split it twice, to create three layers. Place the cake on a thin cake board that’s the same size – it will help when it comes to moving the cake around, and when you are icing it. Fill the cake with the vanilla buttercream, spread it with a cranked palette knife, then leave to set in the fridge for 10 minutes. 
Cover the cake
9. Once set, crumb-coat the cake by spreading a thin layer of buttercream around the outside. Chill again for 10 minutes, then repeat with a second crumb-coat layer. This will give the sugarpaste a smooth finish. 
10. Once it has set, roll out the white sugarpaste to 5mm (¼in) thick on a surface dusted with cornflour. Gently lift it using your rolling pin, then bring it down onto the cake. Using your hands, smooth the icing around the whole of the cake, lifting and smoothing any creases you encounter as you go. Trim off the excess, then smooth the top and sides using plastic smoothers. Leave to set, preferably overnight. If you want to use a cake board, ice it now. I recommend using a 23cm (9in) board for this cake, but if you want to add a message to the board you can increase it to a 25cm (10in) board.
Create and apply the stripes
11. The following day, once both the cake and the board are set, stick the cake to the board using a little royal icing. To decorate with zebra stripes, roll out black sugarpaste and cut out random stripes using a pizza wheel. Stick the stripes to the cake using a little edible glue – I made large stripes from the bottom to halfway, then from the top middle and down the sides. Add any smaller stripes where required. 
Try not to use too much edible glue, as when you stick black paste onto white, it can create black streaks if there is too much glue and the stripes move. Less is more. Once this is done, leave to set completely. Cut into your rainbow zebra cake and admire your colourful masterpiece! 
