Combine water, lemon juice and sugar in a shallow bowl, stir to dissolve the sugar, then set aside.
60 ml water, 60 g granulated sugar, 60 ml fresh lemon juice
Place thickened cream, mascarpone, vanilla and icing sugar into a large bowl and beat until stiff peaks form (see my notes for directions for a decorative top layer).
250 ml thickened cream, 500 g mascarpone, 60 g icing sugar (powdered sugar), 1 t vanilla extract
Working with one biscuit at a time, briefly dip each biscuit into the lemon syrup, then place onto the base of the serving dish (mine was 24cm x 19cm) in a single layer, cutting any to fit.
300 g ladyfinger biscuits (savoiardi)
Spread half of the lemon curd evenly over the biscuits.
1 cup lemon curd
Then spread over half of the mascarpone cream.
Repeat with the remaining biscuits, curd and mascarpone cream.
Cover with plastic wrap and refrigerate for 4 to 5 hours (ideally overnight).
Scatter over freshly grated lemon zest (if using) and serve.
freshly grated lemon zest