01 -
Combine lemon juice, water, sugar, and lemon zest in a medium saucepan over medium-high heat. Bring to a simmer, stirring occasionally to dissolve the sugar. Allow mixture to simmer for 5 minutes, or until slightly reduced. Remove from heat, pour into a shallow bowl, and refrigerate until completely cooled.
02 -
In a medium saucepan, whisk egg yolks, whole egg, and sugar together until just combined. Whisk in the lemon juice, zest, and salt. Add the butter and cook over medium-low heat, stirring constantly, until the mixture has thickened, about 5-8 minutes. Immediately strain the curd through a fine-mesh strainer into a medium-size bowl. Cover with plastic wrap and refrigerate until completely cooled.
03 -
Using a stand mixer fitted with the whisk attachment, whip the heavy cream until stiff peaks form. Transfer whipped cream to a separate bowl. Return bowl to the mixer and replace whisk attachment with paddle attachment. Add the mascarpone cheese, sugar, lemon syrup, and vanilla to the mixer bowl. Beat on high until combined. Add about a cup of the whipped cream and continue beating until incorporated. Gently fold in the rest of the whipped cream.
04 -
One at a time, quickly dip the ladyfingers in the lemon syrup until soaked but not soggy; arrange in an even layer along the bottom of an 8-inch square dish, lining them up in two straight rows of six. Spread half of the lemon curd on top of the ladyfingers, followed by half of the mascarpone filling.
05 -
Place another layer of lemon syrup-soaked ladyfingers on top of the filling. Spread the remaining lemon curd on top of the ladyfingers. Then spread half of the remaining mascarpone filling on top.
06 -
Transfer remaining mascarpone filling to a pastry bag fitted with a large round tip (or a gallon ziplock bag with the corner cut off), and pipe the filling evenly over the tiramisu. Cover and refrigerate for at least 6 hours before serving.