1/2 cup cornflour
2 tbsp finely grated lemon
zest, plus extra for serving
1 cup caster sugar
1/2 cup limoncello or citron vodka
300ml thickened cream, whipped
600g sponge finger biscuits (savoiardi)
225g pkt white chocolate melts, melted
Extra whipped cream, to serve
3/4 cup limoncello or citron vodka
1 1/2 cups lemon juice
1/2 cup water
1 3/4 cups caster sugar
Whisk cornflour with 1 cup of the milk in a stockpot until smooth. Add remaining milk, eggs, zest, sugar and limoncello and whisk until smooth. Place over a medium heat and cook, whisking almost constantly, for 10-12 minutes or until smooth and very thick.
Allow to cool in pot for 15 minutes, whisking occasionally to prevent a skin forming. Transfer to a large heatproof bowl, cover surface with plastic wrap, then sit bowl in a large bowl of iced water to cool quickly before chilling in the fridge for 3 hours or overnight.
To make syrup, put limoncello, juice, water and sugar in a medium saucepan. Stir over a medium-high heat until sugar dissolves. Bring to the boil and boil for 7 minutes. Set aside to cool.
Whisk custard until smooth. If it is too firm and becomes lumpy, stand at room temperature for 30 minutes then whisk again or use an electric mixer. Add mascarpone and whisk until smooth. Add whipped cream and fold in until just combined.
Reserve 5 sponge fingers for the top. Divide remaining sponge fingers into 3 lots. Dip one-third, 2 at a time, in syrup and cover the base of a 5-litre glass trifle bowl with 2 layers of sponge fingers. Cover with one-third of the custard. Repeat layering with two more double layers of sponge fingers and custard. Place reserved sponge fingers, dipped in syrup, on top. Cover bowl with plastic wrap and refrigerate overnight.
Meanwhile, to make chocolate curls, place chocolate in a medium heatproof bowl over a small saucepan of gently simmering water, making sure bottom of bowl doesn’t touch the water. Stir until melted. Spread chocolate over a smooth flat b oard (back of a clean metal tray is ideal) until about 30cm x 25cm.
Refrigerate for about 20 minutes or until firm but not rock hard. Use a curved ice-cream scoop to drag from top to bottom through chocolate to form curls. If chocolate cracks while making curls, leave out of fridge to soften slightly. Curls can be made up to 1 week ahead and kept in the fridge in a sealed container.
Spoon whipped cream on top of trifle. Sprinkle with extra zest and top with chocolate curls to serve.