Last summer, I had found two very old boxes of "Annie's shells & cheese" in my storage unit.
A cold snap in the fall led to mac & cheese cravings,
and I decided to try a box with
some freeze dried ground beef. :)
Front of the box:

Opened, contents:

Contents of cheese powder packet:

Yes, it had hardened into a solid block, however it didn't smell or taste bad, so I proceeded.
Shells and non-rehydrated beef in pot:

After cooking (using minimal water (just a bit more than enough to cover the pasta)
then adding the cheese powder:

After stirring in the cheese powder plus a generous spoonful of butter powder:

This tasted great, with no hint of age.
The beef was a perfect combo, and I didn't use much.
I've had major mac/shells & cheese cravings since, and plan to buy a few very cheap boxes.
Not yet calculated.