Bring a large pot of lightly salted water to a boil. Add macaroni pasta and cook for 8 to 10 minutes or until al dente; drain.
In a 3 quart saucepan over medium heat, melt butter and stir in flour. Cook for about 1 minute, until smooth and bubbly; stirring occasionally. Mix in milk, cream cheese, salt, pepper, and Dijon mustard. Continue cooking until sauce is thickened. Add cooked macaroni and Cheddar cheese.