The Martell de Sant Eloi, or Saint Eloy's Hammer, is a hammer-shaped brioche cake, stuffed with cabell d’àngel (angel hair) jam or marzipan, and decorated with candied fruit and gelatine;  usually it  also contains a surprise porcelain figure. It is the typical food for the festival of Sant Eloi, on 1^st December, the day when you can find it in Barcelona's cake shops.

Sant Eloi is the patron saint of everyone who works with metal, like blacksmiths, silversmiths and jewellers; so the Catalan cake makers decided to devise a sweet to remind you of the main tool of the metallurgical trades, the hammer, which they sell to celebrate the festival in honour of the saint.