Preheat oven to 180°C (160°C fan/Gas Mark 4). Take 2x swiss roll trays/baking trays measuring approx. 30cm x 20cm and grease and line them with non stick baking paper then also grease the paper.

Crack 3 of the eggs in a large bowl then add 75g of the caster sugar, 1x tsp of vanilla extract, and the Violet food colour gel. Whisk the egg mixture together using a freestanding mixer or electric hand whisk. Whisk for about 5 minutes until the eggs are thick and pale and the mixture has roughly doubled in size. This is called the ribbon stage as the mixture will fall like ribbons when dropped from a spoon.

Take 75g of flour and sieve 1/3 of it into the egg mixture then using a large metal spoon gently fold in the flour until incorporated. Repeat with another third of the flour gently folding in so as not to knock out too much air. Repeat with the remaining flour.

Once all the flour is incorporated, divide the mixture between the two trays and smooth out evenly. Bake in the oven for 7-9 minutes until lightly golden on top. Once the sponges are baked, immediately turn out onto a sheet of baking paper that has been generously dusted with icing sugar, then leave to cool.

Repeat the above sponge making process using each of the colours. You should end up with 10 layer of coloured sponge (2 layers of each colour).

Place all the ingredients in a large mixing bowl and whisk together using a freestanding mixer or electric whisk until light and fluffy.

To layer your sponges, place one violet sponge on a sheet of baking paper that has been generously dusted with icing sugar and placed on top of a chopping board. Thinly spread the sponge with some buttercream then place a sheet of the pink sponge on top. Thinly spread buttercream on top of the pink sponge then place a yellow sponge on top. Spread thinly with buttercream then place a green sponge on top. Spread thinly with buttercream then finally place a sheet of blue sponge on top. Repeat the above with the other 5 sponges so you will have two rectangles of layered cake. Put the cakes into the fridge to firm up and chill.

Grease and line two flat trays with baking paper then grease the paper with oil. Take a large heavy based saucepan and add the sugar, liquid glucose, water and cream of tartar. Stir to combine. 

Put the sugar thermometer in the pan then put on a high heat. Boil the sugar without stirring for about 15 minutes until it reaches 150°C. Meanwhile take 3 heatproof bowls and add the food colouring to each bowl.

Once your sugar mixture has reached 150°C carefully divide the hot sugar between the 3 heatproof bowls. Quickly mix the food colouring in each bowl so you will have a bowl of red caramel, yellow caramel, and green caramel. Working quickly before the sugar sets, spoon out the caramel onto the baking trays in the shape of feathers for the headdress. Put to one side to set.

To assemble the cake, take a plate or cake stand at least 8 inches in diameter. Take one of your stacked sponges and trim the edges. Cut the rectangle in half to make two rough squares. From each square cut three fingers equal in width – approx. 5 cm. Repeat with the other rectangle of stacked sponge.

To stack the cake, make a layer of 3 fingers with the middle finger on its side – glue together with a thin layer of buttercream. Spread the top of the layer with a thin layer of buttercream. Repeat for the second layer but have the two outer fingers on their side with the blue layer facing outwards. Repeat with the third layer but lay the fingers the same as the first layer. You should have 3 fingers spare.

Finish the top of the cake with a layer of buttercream then pipe buttercream kisses around the edge of the cake. Sprinkle the middle with some Bright and Bold Sprinkles then stand in some of your sugar glass feathers so they resemble a carnival headdress.