Chiboust cream is pastry cream with stiffly beaten egg whites folded into it.
It can be flavoured with chocolate, liqueurs, orange zest, and / or vanilla. Vanilla is the most common flavouring.
It can be served plain and chilled on its own, or used as a filling for cakes or pastries. It is used, for instance, in Gâteau Saint-Honoré.
Some recipes now use whipped cream or Meringue Italienne instead of beaten egg white. Some recipes also add gelatin to get a better, longer-lasting set.
In a modern version, you make the pastry cream (only lightly sweetened, as more sugar comes with the egg whites), then add the gelatin (leaf gelatin dissolved in some cold water), then add the flavouring. Then, you beat the egg whites, sweeten them with sugar, and fold them in.
Many people in France now disagree about the best version of Chiboust cream.
Some people speculate that it may have originated with a pastry chef named Chiboust, who had a pastry shop on the rue Saint Honoré in Paris (sometime in the 1840s.)