Preheat the oven to 180C/Gas 4; grease and line a 26cm round cake tin and a square 20cm cake tin
beat the eggs and sugar in a large bowl, until thick and creamy and the beater leaves a trail when lifted from the bowl; fold in the flour and vanilla essence gently but thoroughly; pour 2/3 of the mixture into the prepared round cake tin and the rest in the squash tin; bake for 20-25 minutes in the pre-heated oven; take out of the oven and allow to cool completely before using for the cassata
process the ricotta and icing sugar until creamy; add the candied peel and chocolate chips and refrigerate until ready to use
mix together the ground almonds and caster sugar; add the egg white and brandy and stir well, using your hands, until the mixture comes together and you have a slightly soft almond dough; it should be dry enough to be able to roll out; add a few drops green food colouring and mix well to get an even colour
place the sugar and water in a pan over low heat and stir until the sugar has melted; stop stirring once the sugar has melted and bring the liquid to the boil; boil for 2-3 minutes; allow to cool and add the liqueur; refrigerate until ready to use
line a 26cm cake tin with cling film; roll out the marzipan into a strip about 0.5cm thick and long enough and high enough to line the sides of the tin; it might be easier to roll it out in two halves.
remove the top and bottom crust of the round sponge cake and slice in half horizontally; place one half at the bottom of the cake tin; brush generously with the syrup
slice the square cake and lay the pieces against the marzipan; brush generously with the syrup
fill the centre with the ricotta mixture and place the other half of the round sponge cake on top; brush generously with the syrup and press down gently; cover with cling film and leave in the fridge for at least 2 hours but preferably overnight
to finish the cassata, make the glaze by mixing the icing sugar and water until you get a soft icing; add more water if necessary; take the cassata out of the fridge and flip over onto a serving plate; remove the cake tin and clingfilm and slowly pour the glaze on the centre; spread to the edge; allow to cool and harden before decorating with the candied fruit to your liking.