In a medium saucepan, combine fresh lemon juice, water, and granulated sugar. Over medium heat, stir until the sugar fully dissolves, about 2-3 minutes. Remove from heat and allow to cool.

In a mixing bowl, whip the heavy cream with powdered sugar and vanilla extract until soft peaks form, around 4-6 minutes. In another bowl, mix mascarpone cheese with lemon zest until smooth. Fold in the whipped cream.

Dip each ladyfinger into the cooled lemon syrup for 1-2 seconds. Arrange in a 9x9 inch dish, spread half of the mascarpone cream over, and repeat with another layer.

Cover with plastic wrap and chill for at least 4-6 hours, preferably overnight.

Dust the top with extra lemon zest or arrange candied lemon slices before serving.