Cook the macaroni in salted boiling water according to package directions until al dente, then drain and set aside.
Melt the butter in a large saucepan over medium heat, whisk in the flour, and cook for 1 minute until smooth and lightly golden.
Gradually whisk in the milk and cream, stirring constantly until the mixture thickens and begins to bubble, about 4 to 5 minutes.
Remove from heat, stir in the white cheddar cheese, salt, and black pepper until the cheese melts completely and the sauce is smooth.
Add the cooked macaroni to the cheese sauce and toss gently until every piece is evenly coated.
Serve immediately while hot and creamy for the best restaurant-style texture.