In a bowl, combine fresh raspberries and sugar. Let sit for 10 minutes to macerate.

Gently mash the raspberries with a fork, leaving some whole for garnish.

In a mixing bowl, whisk together mascarpone cheese, heavy cream, powdered sugar, lemon zest, and lemon juice until smooth and creamy.

In a shallow dish, mix lemon juice and water. Quickly dip each ladyfinger into the mixture, ensuring they are moist but not soggy.

Layer half of the dipped ladyfingers in the bottom of a 9x9 inch baking dish.

Spread half of the mascarpone mixture over the ladyfingers, followed by half of the raspberry mixture.

Repeat the layers with the remaining ingredients, finishing with the mascarpone mixture on top.

Cover with plastic wrap and refrigerate for at least 4 hours, or overnight for best results.

Before serving, garnish with additional fresh raspberries and a dusting of powdered sugar if desired.