Cut the bacon into small cubes.
Beat the egg yolks in a bowl, add the grated cheeses.
Brown the diced bacon in a teflon pan, on a medium heat. Set aside.
Boil the Spaghetti in plenty boiling water.
Before draining, remember to set aside a spoonful of pasta water to better toss and stir pasta and sauce.
Drain the pasta al dente, toss in the pan with the bacon. Take then off the heat and add the beaten egg yolks.
Don’t cook them too much, let the egg yolks thicken slowly, adding a little of the cooking water if necessary.
Season with freshly grounded black pepper and serve.