Fettucine Alfredo Larusso

This goes so good with the Porcupine Meatballs. I know it seems weird but they do go together. This recipe also came to me from the Beaver clan.
Ingredients:
4-6 ounces fettuccine noodles (I use more)
4 tbs. butter
2-3 ounces of heavy cream (really about half a small carton is about right)
1 tbs. sour cream (if you use more noodles do 2 tbs.)
2-3 tbs. Parmesan cheese
1 beaten egg yolk

When noodles are almost boiled, melt butter in a shallow frying pan. Add cream and sour cream. Mix and maintain over low heat. When hot, add drained noodles and toss well.
Sprinkle Parmesan cheese over noodles and toss. Mixture will thicken. Add a bit more cream if mixture becomes too thick. Turn off heat and add egg yolk. Mix well. Top with additional Parmesan cheese and freshly ground pepper.