I've never looked at the "Mac & Cheese" (though I think I've seen in a shop for American expats). I assumed you just poured water over it, or something.
Are you saying you still need butter and milk to make it?
In which case, the real thing only requires having cheese (which keeps a fairly long time), flour and pasta (both keep indefinitely) in addition.
I am very well aware, I've made the "real thing" at least 100 times.
I very rarely have enough cheese in my house for mac and cheese, especially the right kind of cheese. If I want to make it from scratch I have to plan ahead. However, I always, always, always have butter and (oat) milk in the house though, 24/7, so boxed mac and cheese is always an option.
I still strongly prefer the taste of boxed, it's simply amazing in an indescribable way.
Are you saying you still need butter and milk to make it?
In which case, the real thing only requires having cheese (which keeps a fairly long time), flour and pasta (both keep indefinitely) in addition.