Cook pasta according to package directions; drain and keep warm.
for sauce, in saucepan combine egg, half and half,and butter. Cook and stir over medium heat until egg mixture just coats a metal spoon (about 6 minutes; do not boil. Immediately pour sauce over pasta; stir gently to coat.
Add cooked bacon, Parmesan cheese, and parsley; stir gently to combine. Season with pepper. Serve immediately.