1) Bring a large pan of water to the boil. In a medium frying pan, heat the oil and sauté the pancetta / bacon and the garlic until the pancetta / bacon renders its fat and starts to brown. Remove and discard the garlic. Keep the pancetta / bacon and its fat hot until needed.
2) Add salt and the spaghetti to the boiling water, and cook until it is al dente.
3) While the pasta is cooking, warm a large serving bowl and break the eggs into it. Beat in the Parmesan cheese with a fork, and season with salt and pepper.
4) As soon as the pasta is done, drain it quickly, and mix it into the egg mixture. Pour on the hot pancetta / bacon and its fat. Stir well. The heat from the pasta and pancetta / bacon fat will cook the eggs.
5) Serve immediately.