An alfajor or alajú (Spanish pronunciation: [alfaˈxoɾ], plural alfajores) is a traditional confection typically made of flour, honey, and nuts. Originally from present-day Spain, it is nowadays found in Argentina, Bolivia, Southern Brazil, Chile, Colombia, Dominican Republic, Ecuador, El Salvador, Southern France, Paraguay, Peru, the Philippines, Uruguay, and Venezuela. The archetypal alfajor entered Iberia during the period of al-Andalus. It is produced in the form of a small cylinder and is sold either individually or in boxes containing several pieces.

According to Spanish philologist and dialectologist Manuel Alvar López, alfajor is an Andalusian variant of the Castilian alajú, derived from the Arabic word الفَاخِر, al-fakhir, meaning luxurious, and, contrary to some beliefs that it originated in the New World, was introduced to Latin America as alfajor. The word had been introduced into Spanish dictionaries in the 14th century.

The publication of historical dictionaries of the Spanish language allows one to document both forms of the original alajur, written as alajú and alfajor. Alajur and multiple geographic variations are sweets made of a paste of almonds, nuts, breadcrumbs and honey. It is possible that alfajor and alajú were Arabisms introduced into the Spanish language in different places and times, and, supposing both came from the same etymology, from a linguistic point of view, alajú is probably an Arabism of Castillian Spanish, and so it is still alive in Cuenca, Toledo, Guadalajara and in la Sierra de la peña de Francia; meanwhile the variation alfajor is Andalusian and Murcian. In the Americas, the word alfajor was not known until the 19th century.

A similar sweet called alaú is found in the Arabic-Hispanic cookbook Kitab al-Tabikh, by an anonymous author.^{[citation needed]} The Spanish grammarian Nebrija noted the word for the first time in his Latin-Spanish Dictionary (1495) as: alfaxor or alaxur. In the 12th century, Raimundo Martin describes in his book Vocabulista another possible etymology of the Hispano-Arabic fasur, meaning "nectar".^{[citation needed]}

The regulations of the Andalusian Ministry of Agriculture allow the use of only pure honey, almonds, nuts, breadcrumbs, sugar, flour and spices, such as aniseed, sesame, cilantro, cloves and cinnamon. The Protected Geographical Indication alfajores are meant to be presented in a cylindrical shape, with a minimum weight of 30 grams (1.1 oz) each, and with a minimum size of about 7 centimetres (2.8 in) in length and a diameter of 1.5 centimetres (0.59 in). Each of them will be protected with a wrapping paper, and the ends made an ornament in a spiral shape with a ribbon out of the same paper. Once individually wrapped, they may be packaged in wood or cardboard boxes, but never in plastic.

In Spain, there are a variety of different recipes for preparing alfajores, but the most traditional contain flour, honey, almonds and several spices, such as cinnamon. Alfajores are most commonly sold around Christmas, but in Medina Sidonia, they are available year-round. The traditional Spanish alfajor has been produced in this town (where it is called an alajú) since ancient times, and the recipe has been traditionally handed down from father to son.

Alfajores are still made by craftsmen in Medina Sidonia using natural ingredients that include honey, almonds, hazelnuts, sugar, flour, and breadcrumbs, and mixed with natural spices. The manufacturing process has been respected following a recipe found by Mariano Pardo de Figueroa in 1786. In Medina Sidonia, the annual production of approximately 45,000 kilograms (99,000 lb) is mostly consumed in the province of Cadiz, but they are also famous in Sevilla, Malaga and Huelva.

On 15 September 2004, protected geographical indication was ratified by the Consejo de agricultura y pesca de la junta de Andalucía and published in the Official Journal of the European Union as Alfajor de Medina Sidonia on 6 March 2007.