Make Lemon Syrup: In a saucepan, mix together freshly squeezed lemon juice, water, and granulated sugar. Heat gently while stirring until the sugar dissolves completely, then set aside to cool.

Whip Cream: In a large mixing bowl, whip the cold heavy whipping cream with powdered sugar and pure vanilla extract. Continue whipping until soft peaks form and it’s light and fluffy.

Prepare Mascarpone: In another bowl, beat the mascarpone cheese with lemon zest until smooth and creamy. Gently fold the whipped cream into the mascarpone mixture, being careful not to deflate the air you've whipped into the cream.

Assemble Layers: Quickly dip ladyfinger cookies into the cooled lemon syrup, just enough to soak them without becoming soggy. Arrange the soaked ladyfingers in a 9x9-inch dish, then spread half of the mascarpone cream mixture over the top. Repeat with another layer of dipped ladyfingers followed by the remaining cream.

Chill: Cover your assembled tiramisu with plastic wrap and refrigerate for at least 4–6 hours, although overnight is best for optimal flavor and texture.

Garnish and Serve: Before serving, sprinkle with extra lemon zest or top with candied lemon slices and fresh mint leaves for an eye-catching presentation.