Cruise ship Fantasia serves more than 800 different dishes to 4,000 passengers every seven days

Very transparent stair of the grand, sweeping staircase on the Fantasia cruise liner is underlit, and studded with Swarovski crystals – at a cost of €2,500 per stair. It's the perfect way to make my entrance. Twice a week, Captain Ferdinando Ponti selects passengers to join him for dinner. Sometimes he chooses guests for political reasons – honeymooners or couples celebrating a wedding anniversary. Sometimes he chooses guests because they pester him. I fall firmly into the second category. What the hell. I'm going to be a guest at the captain's table.

The welcome pack on the Italian cruise liner should have a list of things to avoid saying. "Hello, Captain," for instance. Captain Ponti likes to be addressed as Master. Or "I love your boat" – it's a ship. A ship is a vessel which displaces more than 500 tons. The Fantasia displaces 130,000 tons. And I definitely should have avoided "Can I drive?" According to Captain Ponti, "It's like driving a car at high speed. It needs only the smallest movement to effect the largest change." I've breached ship etiquette. And I'm only on the soup course.

The captain is sat next to his wife, who has been allowed on board Fantasia for the night. Life on board can be a strain. Captain Ponti works stretches of six months at a time. Benedetto Minuto, the executive sous chef aboard the ship, takes the odd half-day off here and there – Genoa, for instance, where he goes ashore for coffee. "And once a month I get to meet my family in Palermo – one of our ports of call. But it's difficult to maintain friendships. You are like a fish out of water. When I go back home to Calabria, everyone has their own routine. I don't fit in."

On the night I am invited to dine with the captain, I am one of 13 to accept. So staff have hurriedly invited an extra person. If 13 people sit down to dinner in Italy, the youngest will die. "The Italians are very superstitious," explains Captain Ponti. "Tuesday, for instance, is an unlucky day. And so is Friday. Don't travel on those days." I ask him why he didn't mention that on the day before – a Friday – when he was sailing the Fantasia from Barcelona to Marseilles. But the baked Alaska arrives, and I lose his answer in my excitement.

The after-party is at the Buffet Magnifico. The doors open at 11.30pm – for passengers who want to photograph the food first – but the eating begins at midnight. It pays to arrive early. Regulars know that the fountain of ham won't be around forever. Nor will the chicken musicians, with their heads of lemon, beaks of carrot and eyes of radish. Looking down on the crisp salads, cured meats and cheeses from around the world are aubergine cockerels and carved watermelon faces with hair made from octopus – of such excess, modern-day cruising is made.

The food has been produced in the Fantasia's three main galleys – or kitchens – on decks five, six and 14. I used to skin peas in a restaurant kitchen. I didn't even know that peas had skin, but as a trainee, I was there to learn. In a cramped, low-ceilinged basement, chefs danced between hotplates, carrying heavy metal pans, while sauces steamed over the brilliant blue flames. The head chef stood at the pass, shouting as every plate went out. But the kitchens of the Fantasia – the biggest and best cruise liner in the Mediterranean Shipping Company (MSC) fleet – aren't like that.

They're calm. And quiet. Even though there are 18 different nationalities at work, from Nepalese to Guatemalan. "You would expect communication to be a problem," says Minuto, "and I do find the Indian guys a bit difficult to understand – their English pronunciation is a bit tricky – but we work round it." Rather than risk being misunderstood, the crew works in near silence. The kitchens on the Fantasia are quite the most serene I've ever witnessed.

Even though they're also the busiest. The Fantasia carries 4,000 passengers on its seven-day cruise round the ports of the Mediterranean. Plus a crew of 1,300. And they all need feeding. "It's like a small city," says Minuto. "On the ship, people eat five times a day. There's breakfast, lunch, tea, dinner (two sittings – 7.15pm and 9.45pm) and the Buffet Magnifico. So we have one team that works in the day and one that works in the night, prepping for the next day. That's why we work seven days a week. We never really stop."

One night, Minuto was woken at 2am by a call from one of his kitchen assistants. A pregnant woman wanted a plate ' of pasta. "So I got dressed very quickly," says Minuto. "When a pregnant woman asks for something in Italy, you give it to her. If she craves strawberries and you don't give her strawberries, the baby will be born with a strawberry-shaped birthmark. So I prepared a special sauce with onion, extra-virgin olive oil and cherry tomatoes. At 2.30am. I was delighted – I still managed to get it al dente."

The Fantasia serves up 800 different dishes over a week. That's why the chefs work from a "bible", similar to those used by multinational fast-food outlets. With large type and wipe-clean pages, it shows exactly what the finished dishes are meant to look like. It's not a luxury – it's a necessity. "We had to teach the guys from Nepal and Guatemala how to prepare a bolognese sauce," says Minuti. "The Muslims were even harder to teach. They didn't eat pork. How can you learn to cook something when you can't taste it? But we managed – somehow."

The taller the toque, the more important the chef. And Antonio Armocida's toque is the tallest in the place. The Fantasia's head chef used to prepare fresh pesto for Frank Sinatra – apparently Armocida sent him 50kg a year – but now he's the king of the pasta sauce. It's freshly made, from fresh ingredients, and cooked (on a low heat) for three hours. "The average weekly weight gain aboard the Fantasia is 5kg," smiles Armocida. Clearly, he's doing his job properly.

His kitchen is immaculate. It feels like an institution. Everything is made from stainless steel – even the ceilings and walls. And where the walls join the floor is a strip of coving, to make the place easier to disinfect. An isolated case of food poisoning on a cruise ship is a serious matter. But isolated cases rarely remain isolated. "I have heard about cruise ships where they needed to dock the ship to clean it because of all the vomiting and diarrhoea," says Minuto. "And we really don't want that. It's not good for business."

Every day, a health-and-safety official checks that the food in the fridges and freezers is covered, and that the shelf-life is clearly labelled. Every month, a specialist medical team comes on board to check the hands (more specifically, the skin and nails) of every member of the kitchen crew. They site handwash in all the public areas, and scan the kitchens with special light equipment to check for bacteria. The ship's sanitation is exemplary. And it's why the Fantasia has been free of any major food scares since it first launched in 2008.

I wake up to the hiss of water – the ship is being washed down. It's a misty morning in the port of Genoa and the faithful are being called to mass. The old red-brick buildings of the city are scrambling toward the sky, and my port-side balcony overlooks it all. Genoa is the Fantasia's home port, where the ship takes on its provisions for the forthcoming cruise. As the new passengers board, four forklifts work busily at the dockside to load the contents of 15 articulated lorries on to the ship.

Alberto scans the palettes of food and drink with his metal detector while Jhon, the pest controller, looks under the palettes with his torch. He nods, takes a pace back, and sprays each with Gentrol. Gentrol disrupts the normal growth development of cockroaches, drain flies and fruit flies, and kills stored-product pests such as Indian meal moths, rice moths, red flour beetles, lesser grain borers, merchant grain beetles and sawtooth grain beetles. Which is good to hear. Then the palettes are lifted into the ship's storage area.

The crew loads crate after crate of chicory, fennel, garlic and pumpkin. And huge wooden containers of melons – honeydew, ogen, charentais and galia. Fantasia sells itself on freshness. And the storage area smells like a produce market. There are soft, fleshy peaches, and plump strawberries – even a few raspberries – and they are all loaded into store at 3°C. "Well away from the ventilator," says Antonino, the provision master. "It makes them last longer." Bananas are moved to the dry-food area. They give off a gas which ripens other fruit prematurely.

There is no fresh fish or fresh meat. Everything is brought on frozen, and defrosted when needed. But very few things are pre-made. Bakers on the Fantasia use flour and yeast – rather than frozen dough – to produce nine different types of bread, including grissini, ciabatta and pumpernickel. And they bake their cakes from scratch. That's why they took on 8,745 litres of milk and 26,370 eggs in Genoa. As well as fresh vanilla pods, and hunks of dark chocolate. For cruise-liner food, the Fantasia is as good as it gets.

But one young German couple aren't happy. They have just checked in to the Yacht Club, MSC's blue-riband class – where the coffee comes with a tiny foil-wrapped chocolate, and canapés are available 24 hours a day – and they don't like the complimentary wine. It's Italian. And they want French. The concierge explains how he used to dole out €60 bottles of Bordeaux, but the privilege was abused. He got through 200 cases a week because Yacht Club members were giving it to non-Yacht Club members. It happens.

People have a habit of behaving oddly around complimentary food and drink. Take the Fantasia's all-you-can eat buffet. I learnt the art of all-you-can-eat at the Harvester. I never wanted to appear greedy by going back for seconds, so I treated it as an exercise in structural engineering. One particularly good week – an early-bird special, as I remember – I piled everything up just right and came away with a construction that rose a full four inches off the bowl. Compared to the passengers on the Fantasia, I was an amateur.

In the Zanzibar – the ship's all-you-can-eat buffet, included in the price of the ticket – the plates are as big as trays. And they demand filling. So people circle, see what's good, and engage. All the rules about basic food combining (like jelly and pilaf not working well together, for instance) are forgotten. After all, the jelly and the pilaf might not be there when you come back for seconds. Once plates are full, the passengers rush back to their tables before their jelly and pilaf run into each other. It's chaos.

But you want a bit of chaos in your buffet. It means the food is getting eaten, and replaced, quickly. What you don't want is a buffet where the food sits around. The basic buffet rule is that hot foods must be kept above 140°F, and cold below 40°F. Between the two temperatures, harmful germs grow rapidly. So, rather than take any risks, the Fantasia throws away any perishable foods left out longer than 120 minutes.

The ship takes on 40 tonnes of fruit and vegetables for its seven-day cruise of the Med. And, of that, 10 per cent to 20 per cent is wasted. Because of basic food hygiene, some waste is inevitable. The Fantasia does its best to minimise it by closing sections of the buffet when passenger numbers drop below 500. But a lot more waste is down to pure greed. Because they've paid for it, passengers take more than they can actually eat. To see plate after plate of barely touched food being scraped into a bin, is an affront.

The buffet chefs at the Zanzibar have created a menu of dishes that don't mind standing around. "Oven-cooked pasta – lasagne or cannelloni – works really well on a buffet," says Minuto. The dishes sit at the buffet in a bain marie to keep warm, but they're also heated by the bright overhead lights. "And that means they can overcook. That's why we do most of our fish or meat with sauce. It's to prevent the food drying out."

The tomatoes in the salad bar are ripe, the lettuce crisp, and the extra-virgin olive oil kept separate from the vinegar. Even though the Fantasia sails in international waters, there are some things the Italians just won't compromise on. In Genoa, the buffet chefs take a risk by serving up aglio e olio. The spaghetti dish is made by lightly sautéeing pressed garlic in olive oil with chilli flakes. It's simple to do, but it's hard to get right. Let alone keep warm. And al dente. But it is a triumph, and the vat of spaghetti goes in five minutes.

Jeff and Patrina Dawkins from Windsor are finding the buffet a little raucous. Even thought they're cruise veterans. "We didn't actually notice the food," says Jeff. "To be fair, we went along just as people were arriving on the ship. They had probably been travelling all day and were hungry. So it was a bit more chaotic than usual." Patrina wasn't bothered. But then, she was watching her calorie intake. "You always eat too much on day one and day two," she says. "Then you moderate things. This morning I had sliced fruit for breakfast."

Barbara and Marjorie, two friends from Wales, don't like the pushing and shoving at the buffet either. But their only real complaint is the lack of tea-making facilities in their room. "We do like our tea on tap, all day long," says Barbara. Diane from Leeds suffers with allergies. But she feels well catered for on the Fantasia. "My only complaint – apart from the uncomfortable sun loungers – is that, at the end of dinner, I really felt there should be crackers with the cheese. I'll be back – but next time I'll bring my own crackers."

For more on MSC Cruises: tel: 0844 561 1955, msccruises.co.uk