In a saucepan, combine lemon juice, water, and sugar over medium heat until sugar dissolves. Remove from heat and let cool.

In a large mixing bowl, whip heavy cream with sugar and vanilla until soft peaks form. In another bowl, beat mascarpone and lemon zest until smooth. Fold whipped cream into mascarpone until combined.

Dip ladyfinger cookies in lemon syrup for 1-2 seconds. Layer in a 9x9-inch dish, then add half of the mascarpone cream, followed by another layer of ladyfingers and remaining cream.

Cover with plastic wrap and refrigerate for 4-6 hours or overnight for best results.

Remove plastic wrap and garnish with lemon zest or candied lemon slices before serving. Enjoy!