Bitto

Bitto is a semi-cooked raw cow's milk cheese made exclusively on alpine summer pasture in the province of Sondrio, in Lombardy, plus a handful of mountain municipalities in the provinces of Bergamo and Lecco. Wheels run from 8 to 25 kilos, 30 to 50 centimetres across, with a concave side that is its visual signature: no other Italian cheese has those inward-curving flanks.

The DOP imposes three constraints almost no other Italian denomination accepts. Production is allowed only from 1 June to 30 September, the months the cattle are up on the mountain. The milk must be worked immediately after milking, on the pasture itself, with no transport down the valley. And up to 10% goat's milk may be added, from the Orobica breed, a native endangered mountain goat whose milk is fatty and aromatic.

Minimum ageing is 70 days, but Bitto is one of very few Italian cheeses that genuinely improves for years: five, eight, ten. Old wheels turn rock-hard and grateable, and the flavour drifts away from milk towards dried fruit, beef broth and toasted nuts.

Young Bitto, at three to six months, tastes of butter, hay and mountain herbs, with a nutty sweetness and a clean lactic finish. The texture is firm but supple, with scattered small eyes. If the wheel carried goat's milk, there is a faint tang that lifts everything without reading as goaty.

At two to three years it becomes savoury and deep, with brown-butter, hazelnut and dried-mushroom notes, tyrosine crystals that crunch, and a long finish that turns almost meaty. At five years and beyond it is closer to a very old Comté or a wheel of aged Gruyère d'alpage than to anything else Italian: intense, dry, saline in a mineral rather than salty way.

Across every age there is a herbal, alpine top note that comes from pasture rather than technique. It is the most obvious argument for why the June-to-September rule exists.

Young Bitto is a melting cheese. In pizzoccheri, the buckwheat pasta of the Valtellina layered with cabbage, potatoes and butter, it gives short, clean strings and does not weep water. In polenta taragna it is stirred in at the end, off the heat, until the polenta turns glossy.

Past a year it stops being a cooking cheese and becomes a tasting one. Break it into shards with a knife point, serve with rhododendron or chestnut honey and walnuts, or grate a very small amount over a barley soup. Five-year wheels function almost as seasoning: a few flakes on bread and olive oil are enough.

The one rule that matters: never put it over direct heat. Above about 70C the fat separates and you are left with a rubbery mass. Layer it with hot ingredients and let residual heat do the work, or melt it in a bain-marie with a splash of milk. Take it out of the fridge thirty minutes before serving.

Bitto is made to be kept, and cellars in the Valtellina hold whole wheels for years at 10 to 14 C in high humidity. A vacuum-packed piece keeps at 4 to 8 C until the date on the pack, which the seller sets. Once it is open the wrapping matters: waxed or greaseproof paper first, then a box that is not airtight, in the warmest part of the fridge. Cling film pressed straight onto the paste makes the surface sweat and go slick within days, which is the one thing to avoid.

A young piece holds two to four weeks and an aged one considerably longer. What happens over that time is drying: the cut face pales, hardens and turns slightly translucent, a thin skin forms that is pared off with a knife before serving, and at room temperature the fat beads out as small drops. Dry bloom on the rind lifts with a cloth dipped in vinegar. Freezing does not suit the paste, which crumbles when thawed and no longer slices; grated aged Bitto keeps six months at minus 18 C with a clear loss of aroma.

Look at the side of the wheel first. Bitto has a concave heel, a waist that curves inward, left by the wooden band it was pressed in, and the rind carries the Bitto mark with the year of production branded on it. The rind is thin and straw-coloured on a young wheel and turns amber to brown with age. Cut, the paste is ivory to deep straw, compact, with small scattered eyes. The goat's milk that can make up part of the mix gives a distinct edge behind the sweetness, and older wheels turn dry and nutty with crunchy crystals.

Valtellina Casera DOP is the cheese most often mistaken for it: same valley, but made in the valley dairies rather than in summer huts, with straight flat sides and a milder paste. Beyond Italy the shelf neighbours are Gruyere, Comte and Fontina, all alpine, all different animals and cures. There is also a second name to know, the Storico Ribelle from the Valli del Bitto, made only in alpeggio. Any of these costs several times a supermarket alpine wedge, and old wheels are among the most expensive cheeses in Italy.

Bitto is a genuinely scarce cheese, and total DOP output is small: a few hundred tonnes a year against tens of thousands for the big industrial names. In the US it appears at Murray's Cheese, Formaggio Kitchen, Eataly and specialist importers, usually at $30 to $50 per pound, and often only in autumn when the summer wheels come down.

In the UK, Italian delicatessens, La Fromagerie and online alpine-cheese specialists carry it at roughly £40 to £70 per kilo. Storico Ribelle is rarer still and priced accordingly.

Buy on two pieces of information: the vintage year, which is branded on the rind, and whether the wheel is Bitto DOP or Storico Ribelle. Both are worth buying; they are not the same cheese and should not be the same price. Check the concave side: it is the quickest authenticity test there is.

Gerola Alta and Albaredo per San Marco, in the Valgerola, are the villages of the Bitto valleys. The collective ageing cellar in Gerola Alta holds wheels going back years and can be visited; in summer you can walk up to alpine pastures where the calècc is still in use and the morning milk is being worked at 1,800 metres.

Morbegno, at the mouth of the valley, hosts the Mostra del Bitto every October: part fair, part competition, part market, and running since 1906. It is the one day of the year when dozens of vintages sit side by side.

On the Bergamo side, the upper Val Brembana (Valtorta, Ornica, Mezzoldo, Foppolo) is inside the DOP zone and is reached over the Passo San Marco, the old Priula road built by Venice to link Bergamo with the Valtellina. Many pastures sell directly through the summer.