One of the most popular stories surrounding the origins of spaghetti alla carbonara is that it may have been prepared as a hearty meal for Italian charcoal workers – the carbonari (charcoalmen) – and that the black pepper represents the charcoal.

There are also reports the dish was created using soldier's rations during the Allied occupation of Rome during World World II. Regardless of the many tales surrounding its creation, the dish has evolved into a much-revered classic. The dish has been on the menu at Candelori's​ since the restaurant opened its doors in Smithfield 16 years ago. Chef Christian Candelori​ shows Carla Grossetti​ how it's done.

Crimes against carbonara

Candelori says adding cream to carbonara is the biggest no-no, as the creaminess of the pasta dish should only come courtesy of the raw egg and the addition of some of the reserved cooking water.

"Eggs are the unsung hero of a carbonara. In Australia, carbonara has been made with cream and bacon and some people even use onions to give it sweetness, but that's nowhere near the original, traditional spaghetti carbonara," says Candelori.

"The No. 1 thing people get wrong when they make carbonara is to use cream. The second thing is, they might substitute cheap bacon for guanciale Italian cured meat prepared from pork jowl] or pancetta [Italian salt-cured bacon made from pork belly]," he says.

Ingredients for success

Candelori says spaghetti alla carbonara is characteristic of Roman trattoria cooking because it can be put together very quickly. Like many great Italian dishes, Candelori says quality ingredients are also integral to getting it right.

"Spaghetti alla carbonara is such a simple dish but it's because you are limited to using just four ingredients you need to ensure you do not compromise on the quality of those ingredients," he says.

"Carbonara comprises great eggs, great smoked pancetta, beautiful pecorino cheese and lots of cracked pepper. Because it's such a simple dish, a lot of flavour comes from the pancetta. But you won't get that beautiful buttery, smokey flavour from the pancetta if you use a cheap bacon or cheap pancetta," he says.

Getting started

Candelori says carbonara is so quick and simple to make that people often underestimate the technique required to bring it together. He also says that adding a generous amount of salt to the boiling water for the pasta is another element of the cooking process that is often overlooked.

"If the water you have used to cook the pasta has no salt, the dish will not come together. There are elements that bring the dish together and salt is up there at the top of that list. It's like buttons on a shirt. As beautiful as a shirt may be, if it doesn't have buttons, it won't come together," he says.

After putting a large pot of water over a high heat to bring to the boil, Candelori recommends placing the pancetta in a really hot pan and letting it braise until it is golden. After removing the pancetta from the heat, the next step is to add two egg yolks and two whole eggs to a small bowl and whisking together with a handful of pecorino until the mixture has emulsified.

Cooking the pasta

Like most great Italian dishes, Candelori says there are techniques you can adhere to in order "to apply and maintain a consistency that will take the dish from good to great".

Most dried pasta manufacturers specify a cooking time, but Candelori suggests testing the pasta after eight minutes and never cooking it for longer than 10 minutes to ensure it is al dente. He says retaining a glass of the cooking water after straining the pasta is also crucial to the success of the dish, as it helps achieve the creaminess.

If you use fresh pasta, know that it will cook in a very short time and the term al dente does not apply.

Dried or fresh pasta?

Fresh is always better but if using dried, Candelori recommends the DeCecco​ brand. If people are time-poor, dried pasta is fine. "I like to use spaghettini, as it is a little bit lighter than a spaghetti," he says.

Troubleshooting

After you have drained the pasta, place the pan in which you had the pancetta back over a medium heat. Add half a glass of the residual cooking water, then add the pasta on a medium heat. Candelori says you must continuously toss the pasta as soon as you add it to the pan, so as to cook off all the excess water.

"One of the most common mistakes people make when cooking carbonara is scrambling the eggs. Once the excess water has reduced, take the pasta and pancetta off the heat. You now want to add your emulsified eggs and pecorino and let the residual heat of the pan do must of the work," he says.

Candelori says if the mixture looks too thick, add some more of the residual water but under no circumstances should you put it back on the heat, otherwise the eggs will scramble.

After adding the eggs, the consistency of the sauce should be creamy. If you have scrambled the egg, you can whisk another whole egg and a bit of cooking water and add it to the dish, which Candelori says "should smooth it out so you can recover it".

Equipment

Large pasta cooking pot

Whisk

Cheese grater

Pepper mill

Recipe variations

Some people like to add onion for sweetness, and if you like a bit of spice, Candelori is OK with the idea of adding some dried chilli flakes as long as you "know it is no longer a traditional carbonara".

"A lot of people won't have access to a great deli that has the best quality pancetta, so if you cook it on a day-to-day basis, you can add onion or a bit of chilli to add a bit more flavour," he says.

SPAGHETTINI CARBONARA

Ingredients

360g spaghettini

2 large eggs

2 egg yolks

200g of pancetta

60g pecorino cheese

60g parmigiano

Freshly cracked pepper

Method

Bring to boil 5 litres of salted water and add a generous amount of salt. Add your spaghettini and allow to cook for about eight minutes. Strain the pasta and retain a glass of the cooking water.

Place a frying pan over a medium-high heat, add the pancetta and cook until crispy. While your pancetta is cooking add the eggs, pecorino and parmigiano to a small bowl and whisk until well combined. When the pancetta is golden, remove the frying pan from the heat.

Add the drained, cooked pasta to the crispy pancetta and return to the heat. Slowly add the cooking water and stir the pasta continuously to avoid sticking. This should only be done over a medium heat for a few seconds to remove excess water.

The next step is the most important part of the method and is where a lot of people make mistakes.

Remove your pan from the heat and add in the egg mixture and toss well until eggs have thickened; the residual heat will do most of the work. If the mixture is too thick you can add additional reserved water. Do not place the mixture over the heat, otherwise your eggs will scramble. Taste to see if your pasta needs additional salt, as some pancetta may not be overly salty. Add freshly cracked pepper and grated pecorino cheese and serve immediately.