A small French choux pastry ball filled with cream and topped with chocolate sauce is a profiterole.
Profiteroles are made from pâte à choux, a dough prepared by cooking water or milk with butter and flour before beating in eggs. The high moisture content creates steam in the oven, puffing the dough into a light, hollow shell. Once cooled, each pastry is filled through a small opening or sliced and filled before serving.
Classic fillings include whipped cream, pastry cream, custard, and vanilla ice cream. Chocolate sauce or ganache is especially associated with profiteroles au chocolat, although caramel, powdered sugar, and fruit sauces are also used. A stack of caramel-coated profiteroles forms a croquembouche, a celebratory French pièce montée.
The word has a much older culinary history than the familiar dessert. In the seventeenth and eighteenth centuries, profiteroles could be savory hollow rolls filled with meats, poultry, mushrooms, or truffles and served with soup. The modern cream-filled choux version developed during the nineteenth century.
An éclair uses the same basic pastry but is elongated, while a religieuse is built from two choux cases of different sizes.