Beans!
(are you cooking? and not vegetarian?)
If so: canned soups with meat, chili, tuna, canned chicken - If you're looking for "healthy" there are now lots of organic/healthy canned items out there - Amy's has a lot in their line - check Trader Joes.
(I don't know how Veggies get enough protein - is there Tofu in a can?)

If you drop to "less healthy" (which might be warranted since it is a short time and extreme conditions) there are LOTS of options - Jerky is huge for me - couldn't survive out there without it, LOTS of soup options, chili, canned corned beef hash (YUM!), shelf stable bacon (is this still around?), Raviolios, SPAM!, EZ Cheese :) , canned hams...I'm sure there's tons more.

The thing I have a hard time with is enough Veggies - I'm not a big fan of canned (but I JUST added spinach to my list - thanks!) so I end up drinking a lot of V8 for the veggie vitamins but then you don't really get the fiber.

Oh - I just thought of another fav - Chun King canned chow mien. Meat in one can, veggies in the other - what could be better!

I am bringing my solar cooker for the second year. I brought potatoes, acorn squash, onions, rice, beands, carrots, etc. They all cook up great in the afternoon sun. I'll post a pic of the oven plans, very easy to make. Cooks like nobody's business!

I am bringing ostrich jerkey -- teriyaki and bbq flavors rock. it sounds scary but tastes awesome and has 14g of protein in one stick (plus they're on sale at GNC right now if it's not too late).

Chocolate anything is a mistake if you don't have a cooler. My first burn we brought lots of protein bars with chocolate coating and ended up licking the hot, melted goo off the wrappers in desperation.