Cut the pancetta into strips. In a bowl, put 1 whole egg and 4 yolks. Beat them for a minute with a whisk. Gradually add the grated parmesan while whisking each time. Season generously with pepper.
Heat water in a pot. When it boils, add the coarse salt, then the spaghetti. Let them cook at a boil for one minute less than the cooking time indicated on the package.
In a large skillet, drizzle some olive oil and heat it over medium-low heat. Gently sauté the pancetta slices while the pasta cooks. When the pasta is cooked, drain it while keeping some cooking water. Immediately place the pasta in the skillet with the pancetta and mix well.
Once the pasta is well combined with the pancetta, turn off the heat. Add the contents of the egg-cheese bowl and mix thoroughly.
Add one to two small ladles of pasta cooking water to achieve the desired consistency, which should be a creamy sauce coating the spaghetti. Serve immediately in shallow plates, adding one egg yolk on top. Season with pepper and add grated parmesan.