Brew 4 Earl Grey tea bags in 300ml boiling water.
In a bowl, whisk together the mascarpone cheese, heavy cream, and granulated sugar until smooth.
In a separate bowl, whisk the egg yolks into the mascarpone mixture.
In another clean bowl, whisk the egg whites until stiff peaks form.
Gently fold the whisked egg whites into the mascarpone mixture.
Dip the ladyfinger biscuits briefly into the brewed Earl Grey tea.
Arrange a layer of soaked ladyfingers in the bottom of a serving dish.
Spread half of the mascarpone mixture over the ladyfingers.
Repeat with another layer of soaked ladyfingers and the remaining mascarpone mixture.
Sprinkle lemon zest over the top.
Chill for at least 2-3 hours, or preferably overnight, before serving.