In a small saucepan, combine ½ cup of water and ½ cup of granulated sugar over medium-high heat, stirring until the sugar dissolves, about 2-3 minutes. Remove from heat and stir in ½ cup of limoncello and 2 tablespoons of fresh lemon juice. Allow to cool slightly.

In a large mixing bowl, beat 1 cup of chilled mascarpone cheese on medium-low speed until it loosens, about 1 minute. Mix in ½ cup of lemon curd, 3 tablespoons of limoncello, and 1 tablespoon of lemon juice until fully combined.

In a separate bowl, whip 1 cup of heavy whipping cream with ¼ cup of powdered sugar on medium speed until stiff peaks form, about 3-5 minutes. Fold one-third into the mascarpone mixture, then gently fold in the remaining whipped cream until no streaks remain.

Dip each ladyfinger cookie quickly into the cooled limoncello syrup and arrange half in a single layer in a 9x13 inch pan. Spread half of the mascarpone cream mixture over the ladyfingers, then repeat with the remaining ladyfingers and cream layer.

Cover with plastic wrap and refrigerate for at least 4 hours, preferably overnight.

Before serving, top with additional whipped cream and sprinkle fresh lemon zest over the top. Serve chilled.