Pastry cream, also known as crème pâtissière, is a rich and creamy custard used in various desserts. It is made by cooking a mixture of milk, sugar, egg yolks, and cornstarch until thickened. This versatile filling can be flavored with vanilla, chocolate, or fruit purees, making it suitable for pastries, tarts, and cakes. Once prepared, pastry cream can be cooled and used as a filling for eclairs, cream puffs, or layered in napoleons. It can also serve as a base for other desserts, such as mousse or panna cotta. Properly stored, it remains fresh for several days in the refrigerator.