An American classic. Think outside the box!
Cook macaroni according to package directions. Meanwhile, in a large saucepan, melt butter. Stir in flour until smooth. Gradually add milk and stir until all lumps have dissolved. Bring to a boil; cook and stir for 2 minutes.
Reduce heat; stir in the sour cream, processed cheese, cream cheese, Parmesan cheese, salt, and pepper until cheeses have melted. Gradually add cheddar cheese, and stir until cheese has melted and sauce is smooth.
Drain macaroni and add to sauce and mix well. Transfer to a greased 3-quart baking dish. Bake, uncovered, at 350 degrees for 30-35 minutes or until bubbly.