Cantucci (also called biscotti di Prato, after the Tuscan city most associated with their production) are the twice-baked almond cookies that, paired with a glass of vin santo for dipping, form the quintessential Tuscan dessert ritual—a combination so embedded in the region's culinary identity that ordering one without the other in a Tuscan trattoria would provoke gentle bewilderment. The cookies are made from a lean dough of flour, sugar, eggs, and whole almonds (un-blanched, with their skins on), shaped into flat logs, baked until firm, then sliced on the diagonal into oblong biscuits and baked again until completely dry and golden. This double baking (bis-cotto) produces their defining characteristic: an extreme hardness and dryness that makes them virtually indestructible (they keep for months in a tin) but also renders them nearly impossible to eat without dipping in liquid. This is by design—the cantucci are meant to be dunked in vin santo (Tuscany's holy wine), the amber, oxidative dessert wine made from Trebbiano and Malvasia grapes dried on racks before pressing and aged in small sealed casks (caratelli) for 3-10 years. The dipping softens the cantuccio while the wine penetrates the porous crumb, and the combination of the almond cookie's toasty, sweet crunch with the vin santo's honeyed, oxidative complexity creates a dessert pairing of perfect complementarity. The almonds should be left whole—not chopped—so that each bite includes both the crunchy cookie crumb and a whole nut. Authentic cantucci contain no butter, no oil, no leavening—the texture comes entirely from the double baking and the eggs' binding properties. The city of Prato considers itself the canonical home, and the Mattei bakery (established 1858) is the most famous producer.
Lean dough: flour, sugar, eggs, whole almonds—no butter or oil. Shape into logs, bake once, slice diagonally, bake again. Must be very dry and hard. Serve with vin santo for dipping. Almonds left whole, not chopped.
The dough should be stiff—don't add extra liquid. Let the first-bake logs cool for 10 minutes before slicing—they'll be cleaner cuts. The diagonal cut should produce slices about 1.5cm thick. A few drops of orange zest or anise in the dough are traditional variations. Store in a tin—they keep for weeks.
Adding butter or oil (makes them soft—wrong). Chopping the almonds. Under-baking the second time (not dry enough). Serving without vin santo. Using blanched almonds (the skin adds flavour and colour).
Pellegrino Artusi, La Scienza in Cucina; Carol Field, The Italian Baker