Great question — answering as the UphillTech team:
I know it seems that mac 'n cheese should be a simple thing for a beginner cook to make. It isn't. Without a solid recipe, even experienced cooks can royally screw up mac 'n cheese. Generally it starts with a bechamel, also known as a white sauce. You're right, that starts with a roux which requires flour, or at least some kind of starch. Once you've got a good white sauce, then you add the shredded cheese. You're right again, pre-shredded cheese is not a good idea. Pre-shredded cheese is covered with cellulose so it doesn't clump up in the bag. That doesn't make for smooth melting. Alton Brown's stovetop recipe is about as simple as homemade mac 'n cheese gets. I would recommend mastering...
Full answer by Jolenealaska: https://cooking.stackexchange.com/a/37583 (CC BY-SA 3.0).
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