In a stand mixer bowl, whisk the egg whites with a pinch of salt until stiff peak form.

In a medium bowl, whisk the egg yolks and powdered sugar together until light and creamy with a hand mixer. Add limoncello, lemon juice, mascarpone cheese, heavy cream, and lemon curd, and whisk until smooth and well-combined.

Carefully fold in the beaten egg whites until everything is fully incorporated. Set aside.

In a shallow bowl, whisk together the warm water and powdered sugar until the sugar dissolves. Mix with the limoncello and lemon juice. Set aside.

Dip each ladyfinger quickly into the limoncello syrup, making sure to soak both sides without oversaturating them.

Arrange the soaked ladyfingers in a single layer at the bottom of an 8x8-inch (or similar-sized) dish.

Spread ⅓ of the mascarpone cream over the ladyfingers in an even layer.

Drizzle the cream layer with half of the lemon curd and gently swirl it through with a spoon.

Add another layer of soaked ladyfingers on top.

Spread the ⅓ of mascarpone cream over the second layer of ladyfingers.

Drizzle the top with the remaining lemon curd and swirl it through.

Pipe the remaining mascarpone cream in shape as desired on top of the lemon curd layer. Sprinkle lemon zest on top.

Refrigerate the Limoncello Tiramisu for at least 4 hours, or overnight, to allow the flavors to meld.