In a small bowl, cream the soft butter by beating it against the sides of the bowl with a wooden spoon until it is soft and fluffy.
In another small bowl, beat the eggs and egg yolks with a fork or whisk until they are well blended, then stir in 1/2 cup of grated cheese.
Set both bowls aside.
Heat a large ovenproof serving bowl of casserole in a 200 degree oven.
At the same time, bring the water and salt to a bubbling boil in a large soup pot or kettle. Drop the spaghetti into the boiling water, cook it until they are done.
Meanwhile, fry the pieces of bacon in a pan until they are crisp.
Stir into the pan the cream.
Bring the cream to a simmer and keep it warm until the spaghetti is done.
When the spaghetti is cooked, drain it thoroughly in a large colander, lifting the strands with two forks to make certain all of the water runs off.
Transfer the spaghetti to the heated serving bowl and stir in the creamed butter, tossing and turning the spaghetti with two forks to coat
every strand.
Then stir in the hot bacon-and-cream mixture and finally the beaten eggs and cheese, mixing everything together thoroughly.
The heat of the pasta and other ingredients should cook the raw eggs on contact.
Taste and season with salt and a few grindings of pepper.
Serve the carbonara at once with the remaining 1/2 cup of grated cheese passed at the table.
Taken from:
Recipes: The Cooking of Italy (Time Life Books)