What can I do with super salty cream cheese mixture?

This is too salty to be worth salvaging. You could use small quantities of the mixture in place of salt in recipes where the cheese would be complementary. But since it is so salty you cannot use very much; it would take weeks to get through it all. Salt is pretty cheap, so instead, I would just discard the mixture.

To go with your quiche idea, take a look at a few recipes. They use between 1 and 2 teaspons of salt for a single large quiche. Since you have a cup of salt to deal with, this is 48 teaspoons, or at least 24 quiches! I assume you do not want to bake this many.

I think your idea with the spinach and eggs is probably workable, so long as you only use a little.

You could mix some of it into soups, chowders, white sauces for pasta, biscuit batters, and many other savory dishes. Maybe even gravy. I'd probably even add it to spaghetti sauce and chili, but that would be unconventional. Just don't use all of it at once (as Benjamin already indicated; use as much as you need until there's enough salt in the dish—then don't add more). With all that salt, it shouldn't go bad any time soon. So, you shouldn't need to hurry.