In a saucepan, combine freshly squeezed lemon juice, water, and granulated sugar. Heat over medium heat, stirring until the sugar completely dissolves (about 3-5 minutes). Remove from heat and let cool.

In a mixing bowl, whip the heavy whipping cream with powdered sugar and vanilla extract until soft peaks form (about 4-6 minutes). In another bowl, beat mascarpone cheese with lemon zest until smooth, then fold in the whipped cream.

Quickly dip ladyfinger cookies in the cooled lemon syrup (1-2 seconds per side). Arrange a layer of soaked cookies in a 9×9-inch dish and spread half of the mascarpone cream on top. Repeat the layers.

Cover the dish and chill in the refrigerator for at least 4-6 hours, preferably overnight for best results.

Before serving, garnish with extra lemon zest or candied lemon slices. Slice and serve the tiramisu to enjoy.