Separate the eggs. Beat the yolks and and vanilla extract with an electric whisk until light and foamy. Clean the whisk, then in another bowl whisk the egg whites, gradually adding the caster sugar until it is thick and glossy, a bit like making meringues.
Lightly whip the double cream until it softly holds its shape. Mix with the yolks and egg white mixture until everything is combined. Turn into a container, cover and freeze until solid. Take out of the fridge about 10 mins before serving.