Blend Knorr® Alfredo sauce mix, milk and light cream in 2-quart saucepan. Stir in margarine and bring to a boil over medium heat, stirring frequently.
Reduce heat to low and stir in cheese. Simmer, stirring occasionally, 2 minutes. To serve, toss sauce with hot fettuccine and sprinkle, if desired with freshly ground black pepper, chopped parsley and shredded Parmesan cheese.