Boil the couscous and strain from the water. Beat the eggs with the sugar and add the milk and vanilla sugar to them.
Make the caramel by putting the sugar on the stove to caramelize, pour in the water before removing it from the stove.
Pour the caramel in at the bottom of a cake form, then add the couscous, mixed with the egg mixture.
Bake in a water bath for 50 min. Once it cools well, invert it onto a suitable plate.