In a small bowl, whisk together the lemon curd, limoncello, and egg yolk. Set aside.
In a 4 quart saucepan over medium heat, heat the cream, milk, sugar, and salt, stirring constantly, until near to boiling. Remove from the burner. Pour one third of the cream mixture into the egg yolk mixture, in a steady stream while whisking briskly.
Pour the egg mixture back into the saucepan, stirring quickly. Stir and cook for a minute or two more. In a ramekin add the gelatin to the water and stir until dissolved. Stir the mixture into the saucepan. Heat over medium low or low, stirring constantly for 2-4 minutes more. Remove from the burner before the mixture boils.
Pour through a fine sieve into a clean bowl. Let cool for 20-30 minutes before pouring into ramekins or glassware. Continue to cool completely on the counter.
Cover each with cellophane or store in a large sealed container. Refrigerate for 3-4 hours or until very cold. Decorate with whipped cream, flowers, and berries just prior to serving.