Whisk the whole eggs, yolks, and caster sugar together in a bowl.
Gently melt the butter with lemon zest and juice in a pan over low heat.
Add egg mixture and stir constantly for 10 minutes until thickened.
Strain the curd into a bowl, cover surface with parchment, and cool.
Line a 2 L bowl with overlapping slices of sweet bread.
Drizzle limoncello over the bread and spread cooled lemon curd on top.
Scatter broken meringue nests over the curd and cover with fresh custard.
Whisk cream with icing sugar and vanilla until soft peaks form.
Top trifle with cream, almonds, and candied zest, then chill.