Which of the following is NOT true about tarts?

Tarts are traditionally made using a type of pastry known as pastry dough or sweet shortcrust pastry, which provides a stable structure and a solid base for their fillings. However, puff pastry is generally not used for tarts because its characteristics differ significantly from those ideal for tarts. Puff pastry is light and flaky, ideal for items that require a puffed structure, like mille-feuille or palmiers, rather than the firm base needed for a tart.

Regarding other aspects, tarts are indeed known for their fillings, which can range from custards and fruits in sweet varieties to vegetables and meats in savory versions. Furthermore, they are usually baked in a mold to give them their characteristic shape, allowing for a straight-edged crust and an aesthetically pleasing presentation. This method enhances the tart's overall structure and makes for easier serving.