A croustade is a French culinary term meaning a crust or pie-crust of any type. They are usually made of flaky pastry or puff pastry, but there are also bread croustades, potato croustades, rice, semolina and vermicelli croustades, among others.
The term is derived from the Occitan and Catalan term crostada, which derive from Italian crostata, and the English term custard derives from it.