With a stand mixer or hand held mixer, whip cream with ½ cup powdered sugar, and ½ teaspoon lemon zest. Set aside.
In a clean large bowl, mix together mascarpone, ½ cup of powdered sugar, lemon curd, limoncello, ¼ cup lemon syrup, and 1 ½ tablespoons of lemon zest until fluffy. Fold in half the whipped cream.
In another small bowl, mix remaining lemon syrup with lemon juice.
Dollop about ½ cup of the mascarpone mixture in the bottom of a serving dish.
Using a pastry brush, brush both sides of each ladyfinger with lemon juice mixture, and lay in a single layer on top of the dolloped mascarpone.
Dollop in some of the mascarpone mixture, smooth it out, then top with another layer of lemon brushed ladyfingers. Continue layering mascarpone and lemon ladyfingers until you run out. You should end up with 2-3 layers, depending on the size of your pan.
Refrigerate at least 6 hours before serving. Garnish with lemon slices and additional lemon zest. Serve with dollops of whipped cream.