Boil 500 grams of spaghetti in a large pot of salted water until it is al dente. Drain and set aside, reserving some of the pasta water.
In a separate bowl, whisk together 4 large egg yolks, 100 grams of grated Parmesan cheese, and freshly ground black pepper.
In a large pan, cook 200 grams of diced bacon until it is crispy. Remove the bacon from the pan, leaving the fat behind.
Add the cooked spaghetti to the pan with the bacon fat. Toss well to coat the spaghetti.
Remove the pan from the heat and quickly add the egg and cheese mixture, stirring quickly until the eggs thicken and form a creamy sauce. If the sauce is too thick, add a little of the reserved pasta water.
Add the cooked bacon back into the pan and toss well. Serve immediately, garnished with extra Parmesan cheese and freshly ground black pepper.