In a small saucepan, combine ½ cup of fresh lemon juice, ¼ cup of water, and ¾ cup of granulated sugar. Heat over medium heat until sugar dissolves, about 3–5 minutes. Cool completely.

Whip 1 cup of cold heavy cream with ⅓ cup of powdered sugar and 1 teaspoon of vanilla extract until soft peaks form, about 3–5 minutes. Beat 16 ounces of room-temperature mascarpone cheese with 2 teaspoons of lemon zest until smooth, then fold in the whipped cream.

Dip each ladyfinger in the cooled lemon syrup for 1–2 seconds. Layer in a 9x9-inch dish, covering the bottom. Spread half of the mascarpone mixture over the top, then repeat with another layer of ladyfingers and remaining cream mixture.

Cover the dish with plastic wrap and refrigerate for at least 4–6 hours, ideally overnight.

Garnish with fresh lemon zest, mint leaves, or candied lemon slices before serving.