Membrillo, or quince paste, is a firm, jelly-like confection made by slow-cooking quince (Cydonia oblonga) with sugar until it sets. Quince itself is native to the Caucasus and central Asia, but the paste is most closely associated with Spain and Portugal, where it is called membrillo and marmelada respectively (the Portuguese marmelada is the origin of the English "marmalade," though marmalade itself is now usually made from citrus).
In Spain and Portugal, membrillo is a classic accompaniment to aged sheep's-milk cheeses such as Manchego. It is also used as a glaze for roasted meats, a filling for pastries in the Middle East and North Africa, and a topping for yogurt-based desserts.
Its flavor balances sweetness and tartness with a subtle floral note, and a firm, spreadable texture that slices cleanly. It pairs well with nuts, fresh cheeses like goat and ricotta, and cured meats such as prosciutto or serrano ham.