Step 1

In a small saucepan, bring 1/2 cup water, sugar, and ginger to a boil, 2 to 3 minutes. Remove from the heat and let stand until completely cool.

Step 2

Put the mascarpone in a large bowl and fold it a few times with a large rubber spatula to loosen it. Stir the lemon curd and add it to the mascarpone. Using the spatula, gently fold the curd into the mascarpone until just combined and no streaks of white remain. Add a third of the whipped cream and fold lightly to combine; add the remaining whipped cream and fold gently, turning the bowl, until the mixture is homogeneous and no streaks of white remain.

Step 3

Strain the syrup through a fine-mesh sieve into a shallow dish, pressing on the ginger to remove as much liquid as possible. Add the limoncello to the syrup and stir to combine.

Step 4

Briefly dipping both sides of half of the ladyfingers into the ginger-limoncello mixture (to moisten the cookies but not soak them), line the bottom of an 8-inch (20-cm) square baking dish or cake pan with 6 ladyfingers in 2 rows, trimming the edges to fit if necessary. (Place the trimmings in a small bowl and steal a spoonful of the filling to dollop over them and enjoy as a private little cook's treat.)

Step 5

Pour half of the lemon cream mixture into the pan, and with a small offset spatula, spread the filling evenly over the ladyfingers. Repeat with the remaining ladyfingers, trimming them exactly like the first layer; you may need to flip them over in the syrup in order to dip both sides once the syrup begins to run out. Spread the remaining cream over the top. Lightly cover the dish with plastic wrap and refrigerate for at least 4 hours and preferably overnight.

Step 6

To serve, slice with a warm dry knife.