Preheat oven to 180ºC/350ºF and line cake pans with baking paper.

Whisk together the eggs, egg whites, champagne and vanilla.

Using a paddle attachment, combine all the dry ingredients, butter and half of the champagne mixture.

Continue to mix, then add the remaining champagne mixture after scraping down the sides of the bowl.

Mix until smooth.

Pour batter into lined pans (I used 4 6" pans, or 2 pans at a time).

Bake for 40min or until fork inserted comes out clean.

Remove cakes from the oven and allow to cool, then remove them from the cake pans and allow to cool further on a wire rack.

In a saucepan, bring the 350g of sugar, the champagne and the water to a simmer.

Allow to simmer until it reaches the soft ball stage (about 110ºC).

Meanwhile beat the egg whites with the remaining sugar until stiff peaks.

Once the sugar reaches the soft ball stage, pour the sugar mixture into the egg white mixture while beating on high speed. Make sure you pour the syrup in, in a slow steady stream.

Continue to whip the mixture on high speed until the bowl has cooled down to body temperature (you should be able to hold your hand against the bowl).

Then add the butter blocks to the mixture, one block at a time.

Continue to mix until you have a delicious creamy buttercream.

Cut the heads off of the cakes so that they are all the same size flat on top.

Then place icing on the bottom layer and add another layer and continue to do that until you have four layers perfectly stacked on top of each other.

Place the cake in the fridge for about 15min to allow the buttercream to harden slightly.

Then apply a thin layer of icing around the whole cake (crumb coat), and place the cake back in the fridge for at least another 20min.

To create the ombre effect, divide the remaining buttercream into 4 different bowls.

Mix in 3 different types of food colouring into each one, leaving the last bowl with the original white buttercream.

Remove the cake from the fridge, then starting at the bottom, place the darkest shade of pink roughly around the bottom of the cake (using a piping bag or spatula).

Then add the second shade, then the third and lastly place the remaining white buttercream on the top of the cake.

Then using either a smooth cake scraper or a large offset spatula, gently smooth the cake around, taking off all the excess icing. The colours will start to blend into each other slightly.

Continue to do so until the cake has a smooth appearance.

Place cake in fridge or serve immediately.