This cake is not for the impatient or novice. It involves a lot of time and bowls.

There’s the separating of eggs, whipping of whites for the cake; the whipping of cream for the filling. And there’s the assembly and the frosting of the cake.
The simpler idea would be to brush limoncello over the outside of a lemon or plain pound cake before slicing. But of course I didn’t go that way and discovered an unexpected cake for a special occasion.
For the sponge cake:
1 tablespoon unsalted butter
1 1/4 cups unbleached all-purpose flour
2 1/2 teaspoons baking powder
1/8 teaspoon salt
5 eggs, separated
1 1/4 cups sugar
grated zest of 1 lemon (optional)
2 teaspoons vanilla extract
For the limoncello cream:
9 eggs yolks
1/2 cup sugar
1/8 teaspoon salt
1/3 cup plus 1 tablespoon limoncello
1 cup whipping cream
For garnish:
2 1/2 cups whipping cream
1 1/4 cups sugar
To layer:
6 tablespoons limoncello