To make the creme patisserie heat the whole milk with the seeds from the vanilla pod until it steams. Then take it off the heat
In a food mixer or with an electric hand whisk, whisk up the egg yolks with the caster sugar until pale and thick. Add the cornflour and whisk in, then turn the mixer back on and pour the warm milk in slowly
Pour the mixture back into the pan and heat it up whilst stirring. When it starts to thicken, whisk it to keep it smooth and stop any lumps forming
Put it in a bowl, and covered it with cling film. Make sure the cling film is touching the creme patisserie so that a skin doesn't form on it. Put it in the fridge to cool completely
Pre-heat your oven to 160C Fan/180C/350F/Gas Mark 4. Line and grease a 23cm spring form cake tin
In a food mixer whisk up the eggs with the caster sugar until pale and super thick. This takes around 8 minutes. When you lift the whisk out the mixture that falls off should stay on the surface for 3 seconds before sinking in - this is called the ribbon stage
Fold the plain flour and vanilla extract into the egg mixture very gently so as little air is lost as possible. Then put it in the tin
Bake the sponge for 25 minutes. Leave to cool completely
Cut the sponge into three layers and put the first piece onto a cake stand. Spread a thin layer of the creme patisserie onto it, then pipe a border of the creme patisserie around the edge
Add jam in the middle and spread evenly
Put the second sponge on and spread over more creme patisserie, then pipe a border of the creme patisserie around the edge
Add jam in the middle and spread evenly
Whip up the double cream with the vanilla and icing sugar, and add some of it over the top of the jam
Place the final sponge layer on, then spread the rest of the whipped cream over the whole cake, making a dome shape on top
Knead green food colouring into the marzipan and roll it out, use icing sugar to stop it from sticking to the work surface. Cover the entire cake with it, smooth it down and trim the edges
Melt the dark chocolate and pipe a design on top, and add the pink sugar flowers
Store leftovers in the fridge and eat within 2 days