Rome - In Prato they are proud of their famous biscuits; just don't call them cantucci, even if your name is Pope Benedict XVI.

The German pontiff, noted for his sweet tooth, is reportedly a fan of the slice-like, almond-studded confectionary, a passion he shares with among others, former US president Bill Clinton. Designer Giorgio Armani offers them to visitors at his fashion showroom in Milan.

The cantucci or cantuccini (the smaller version) may have conquered palates beyond the confines of their Tuscan town of origin, but back home they all insist on calling them the biscotti di Prato (the biscuits of Prato).

Debate, however, rages over who and when the biscuits were first baked. Some suggest that cantucci-like delicacies were first mentioned in Medieval manuscripts. Others still, cite the works of Italian Renaissance writer, Giovanni Boccaccio, author of the bawdy Decameron.

According to the most widely accredited claim, Antonio Mattei, invented the recipe when he opened his confectionary shop in downtown Prato in 1858.

The formula, which won a prize for Mattei at the 1867 International Exposition in Paris, consists of flour, fresh eggs, sugar, almonds and pine nuts.

Neither yeast nor fats - including butter, oil or milk - are tolerated as ingredients for the paste, which is first baked, cut into slices and then toasted to achieve the biscuits' typical hard texture.

The misnomer "cantucci" which literally means "the edges" is believed to have first gained currency amongst the poor of Prato who were offered the baker's leftovers, or the edges of the paste deemed too thin to form a proper biscuit.

By the early 20th century, the cantucci's fame was growing with German author, Herman Hesse, describing them in a letter as "this pastry which puts me in a good mood on an otherwise sad day."

Since then, serving cantucci along with a glass of sweet wine - preferably Vin Santo, the so-called Holy Wine otherwise used in the celebration of Roman Catholic Mass - has become a classic way to end an Italian meal.

The biscuits are often dipped into the wine to soften the crust and heighten their aromatic properties.

The Biscottificio Antonio Mattei biscuit factory still stands in its original location, where it has been owned for three generations by the Pandolfini family.

This year they are celebrating the 150th anniversary of Mattei's cantucci, along with their increasing international popularity worldwide.

Exports have soared by 15 per cent over the last year alone, according to Francesco Pandolfini who along with three siblings runs the Biscottificio.

As the business expands, the family says the making of the biscotti continues to honour the "spiritual testament" Mattei left his son Emilio - that the recipe of his "beloved creation" remain unaltered. (dpa)