In a small saucepan, combine ½ cup of freshly squeezed lemon juice, ½ cup of water, and ½ cup of granulated sugar. Heat over medium heat, stirring gently until the sugar fully dissolves (about 2 minutes). Remove from heat and let it cool completely.

In a mixing bowl, use an electric mixer to whip 1 cup of cold heavy whipping cream with ¼ cup of powdered sugar and 1 teaspoon of pure vanilla extract until soft peaks form, taking about 3–5 minutes.

In another bowl, beat 1 cup of mascarpone cheese and the zest of 1 lemon until fluffy, about 2 minutes. Gently fold the whipped cream into the mascarpone mixture, ensuring a light and airy texture.

Briefly dip ladyfinger cookies (Savoiardi) into the cooled lemon syrup for 1–2 seconds. Arrange a layer of soaked ladyfingers in a 9x9-inch dish, covering the bottom. Spread half of the mascarpone cream mixture evenly over the ladyfingers.

Repeat the process by dipping another batch of ladyfingers into the lemon syrup and layering them on top of the mascarpone cream. Spoon the remaining mascarpone cream over the ladyfingers, smoothing it out evenly.

Cover the assembled Lemon Tiramisu with plastic wrap or a lid, and refrigerate it for at least 4–6 hours, or ideally overnight.

Before serving, take the Tiramisu out of the refrigerator and sprinkle fresh lemon zest or arrange candied lemon slices on top for an elegant presentation. Serve chilled.