Curds are usually made from citrus fruits and sugar which are thickened with eggs and butter. They have a thick, soft consistency and can be spread on bread or toast and used like jam or as a filling for a sponge cake or small tarts or other pastries (below). Because the addition of eggs diminishes a curd’s keeping qualities these are not a true pre serve, and should, therefore, be made in small quantities, kept in the refrigerator and eaten quickly – which is not difficult, as they are so delicious.