Bring a large pot of lightly salted water to a boil. Add pasta and cook until al dente, 8 to 10 minutes; drain.
Combine cream cheese, Parmesan, margarine, milk, garlic powder, and basil in a medium saucepan. Stir over low heat until smooth and creamy, 10 to 15 minutes.
Toss sauce with pasta and sprinkle with nutmeg.
