American cheese isn't made of plastic in the sense of polymers, it is plastic in the sense of being easily deformed or molded.
At its most basic, American cheese is literally just cheese, water and sodium phosphate. It's "not cheese", but in the sense that meatloaf isn't meat and mayonnaise isn't eggs.
Man I don't even wanna know what's in the powdered cheese you get in a macaroni box. (I don't eat any cheese cause I'm lactose intolerant, but I always see people just toss the cheese pouch and use their own cheese.)
It's mostly made using spray dryers. Basically, a spray dryer uses hot air to quickly dry a fine mist of something. It's how they make milk powder and egg powder as well.
WTF is wrong with you??? You just grate cheese over pasta and call it a day? The cheese should be melted into a sauce (I start with a bechamel and then add cheese), then mixed into the macaroni. I prefer to bake it with breadcrumbs on top after for some textural variety.
Yeah, bechamel is great too, but I'm lazy. Cheese only is also fine if you let it sit a bit with top covered. It's not dry if you use soft creamy type of cheese. Baking it? Nah - it'll be too soft and melty for my taste, pasta should have texture.
That's not exactly healthy either and but it tastes like it should be. Mac n cheese should be creamy AND cheesy and delicious. What you are suggesting sounds plain and dry, I wouldn't touch with a 10 foot pole unless I was a guest at your house. But you can be damn sure I'd tell everyone you can't make Mac n cheese and I definitely wouldn't trust you with dinner ever again.
You start with a roux add a little milk then cheese then milk and again cheese. Keep doing that until it's cheesey/creamy enough. Good idea to add salt and some seasonings as well.