Put the pot with water for the pasta directly on the fire, because the rest is done in a jiffy.
Fry the guanciale in a pan large enough to stir-fry the pasta.
Beat two eggs and the yolk of the third one, add three spoonfuls of grated pecorino and a pinch of salt. If the texture is more like a dough than a sauce, add a spoonful of cooking water to make the pasta a little more liquid.
Strain the pasta and sauté it with the contents of the pan.
Turn off the heat and add the beaten egg to the pasta and stir. With the remaining heat in the frying pan the egg should have enough to thicken a little, smear the pasta, but without turning into little pieces of omelette. If the egg is too raw, put the paella on the fire for a few more seconds, but still not as thick as an omelette!
Add pepper to taste, stir and serve.