But if you eat all the pastry. . . it remain les feuilles!

The mille feuilles cream is made from milk, egg (sometimes only the yolks), sugar, wheat flour or starch and sometimes butter. Everything is heated, whipped and cooled. It is originally added with vanilla, but the flavor can vary: chocolate, coffee, lemon, etc.
The notable fact is of a nutritional nature, due to the requirements linked to trade (profitability, preparation considered trivial and necessarily accessible by buyers, etc.), the majority of preparations using the name “pastry cream” or marketed without information, do not use the original recipe, some even containing neither milk nor egg, but water, flavors, texturizers and gelling agents.