1. Make the lemon curd: whisk egg yolks, sugar, lemon juice, and lemon zest in a non-reactive bowl over gentle heat until thick enough to coat the back of a spoon.

2. Remove the curd from the heat and whisk in the cubed butter until smooth and glossy. Cover the surface directly and cool completely.

3. Make the syrup: combine water, sugar, and lemon juice and heat until the sugar dissolves. Cool completely, then stir in limoncello if using.

4. Make the mascarpone cream: briefly beat the mascarpone with confectioners’ sugar and lemon zest until smooth. In a separate bowl, whip the cold heavy cream to medium peaks.

5. Fold the whipped cream into the mascarpone mixture gently until smooth and stable.

6. Dip the ladyfingers very quickly in the cooled lemon syrup and arrange a tight single layer in an 8×8-inch or 9×9-inch dish.

7. Spread half of the mascarpone cream over the ladyfingers, then spread half of the lemon curd over the cream.

8. Repeat with another layer of dipped ladyfingers, remaining mascarpone cream, and remaining lemon curd.

9. Cover and refrigerate for at least 4 hours, preferably overnight, until the dessert is fully chilled and sliceable.

10. Garnish with fresh lemon zest, mint, lemon slices, or white chocolate shavings just before serving.