This delicious recipe for fettuccine alfredo comes from Eleanora Scarpetta.
Bring a large pot of salted water to a boil. In a small skillet, heat olive oil over medium heat. Add prosciutto, mushrooms, and parsley. Saute until light golden brown, 8 to 10 minutes.
Melt butter in a small saucepan over medium-low heat. Add heavy cream and cheese. When cheese is melted, add egg yolk. Cook, stirring constantly, until mixture thickens enough to coat the back of a spoon. Remove from heat.
Add fettuccine to boiling water and cook until al dente, according to package directions. Drain pasta and transfer to a large serving platter. Pour sauce over fettuccine; sprinkle with mushroom and prosciutto mixture. Serve immediately.