In a small bowl, mix 3 of the eggs, the parmesan, salt and pepper together; set aside.
Bring a large pan of water to boil, enough to just cover the pasta, add in the fettuccine and cook as per package instructions.
Meanwhile, in a large skillet, over high heat, add the bacon lardons; fry until the bacon is browned and crispy; turn down the heat to low and stir in the garlic.
At this point, if you wish to serve your carbonara with poached eggs, boil a kettle so it’s ready for poaching the remaining 3 eggs.
When the pasta is ready, spoon out all but approximately 1 tablespoon of excess fat from the bacon pan; use a set of tongs to transfer the fettuccine to the bacon pan; using tongs, rather than draining the pasta, transfers some of the pasta water, which helps to thicken the sauce.
Working quickly, pour the egg/parmesan mixture into the bacon pan, then lift and lower the pasta in the pan using the tongs; this should coat the pasta in the egg/parmesan mixture without the egg scrambling.
Add a ladle of the pasta water to the pan, then lift and lower again; this will loosen the sauce slightly; turn off the heat.
If you’re serving the carbonara with poached eggs, pour the pasta water down the sink, then add boiled water from the kettle to the hot pan.
With the water gently simmering, give it a stir, then break an egg into a small bowl and lower the egg into the water.
Repeat with the other two eggs, and simmer for 2 minutes.
Remove the eggs with a slotted spoon, and serve on top of the carbonara along with some parmesan and fresh parsley.