Separate the whites from the yolks.
Whisk the yolks with half the sugar and orange zest. Add the liqueur and orange juice.
In another bowl, whisk the whites, gradually adding the remaining sugar until a thick, stable mass is formed.
Gently combine the beaten egg whites with the yolk cream.
In a separate bowl, whisk the cream.
Combine the whipped cream and the yolk-protein mass.
Cover the mold evenly with plastic wrap so that the ends hang down.
The mixture is spread into a mold. Silicone molds can also be used.
Cover with plastic wrap and put in the freezer for at least 12 hours.
PS It is better to cut with a knife soaked in hot water.