Cook fettuccine pasta according to package directions until al dente. Drain and set aside.
In a large saucepan, melt butter over low heat.
Add flour to the melted butter and heat until mixture becomes bubbly.
Gradually add milk and light cream, whisking continuously to prevent lumps.
Bring mixture to a boil, then reduce heat and simmer for 2 minutes, stirring constantly.
Add parmesan cheese, salt, and parsley, stirring until cheese melts completely.
Toss the cooked fettuccine with the alfredo sauce until evenly coated.
Serve immediately while hot.