In a large mixing bowl, whip the heavy cream until stiff peaks form.
In another mixing bowl, combine the mascarpone cheese, granulated sugar, Italian Volcano lemon juice, lemon zest, and vanilla extract. Mix until smooth and well combined.
Gently fold the whipped cream into the mascarpone mixture until fully incorporated.
If using Limoncello, pour it into a shallow dish. Dip each ladyfinger into the Limoncello briefly, ensuring it gets moistened but not soaked.
Arrange a layer of soaked ladyfingers in the bottom of a 9x9-inch square baking dish or a similar-sized serving dish.
Spread half of the mascarpone mixture over the ladyfingers, smoothing it out with a spatula.
Repeat with another layer of soaked ladyfingers and the remaining mascarpone mixture.
Cover the dish with plastic wrap and refrigerate for at least 4 hours, or preferably overnight, to allow the flavors to meld and the tiramisu to set.
Just before serving, dust the top of the tiramisu with unsweetened cocoa powder.
Slice and serve your delicious Italian Lemon Tiramisu chilled.