Fill a large pot with water and bring to a boil. I add about a teaspoon of salt, but that is up to you.
Cook pasta for the length of time necessary for 'al dente' (about 7 - 10 minutes depending on the pasta shape).
Saute' the butter in a large saucepan.
Add the cream.
Drain the pasta when it is finished cooking.
Pour the butter-cream sauce into the pasta.
Add the egg yolks, three (3) cheeses, and the pepper.
Add the diced prosciutto and peas.
Stir really well, so that all of the pasta is coated with the sauce, yolks, and the rest of the ingredients.
Cook for another minute or two so that the yolks are cooked.
Taste and add any salt and pepper that you desire for your preference level.
Serve immediately with additional grated cheese to pass around.