In a medium saucepan, cook onion in hot butter about 5 minutes or just until tender. Stir in bacon and prosciutto. Cook and stir for 3 minutes more. Carefully add white wine. Bring to boiling; reduce heat. Simmer, uncovered, for 5 minutes, stirring occasionally. Add whipping cream and milk. Bring to a gentle boil.

Gradually add 1 cup of the hot cream mixture to egg yolk, stirring constantly. Add egg yolk mixture to cream mixture in saucepan. Return to a gentle boil; cook and stir for 2 minutes. Add the 2 tablespoons Parmesan cheese and the parsley, stirring just until cheese melts.

Meanwhile, cook the fettuccine according to package directions; drain well. Transfer pasta to a large serving bowl. Pour sauce over hot pasta; toss to coat. If desired, sprinkle pasta with additional Parmesan cheese and cracked black pepper. Makes 4 servings.