For the protein powder, you can premeasure some powdered milk to go with.  I suggest adding a little sugar to it as the powdered milk seems to be an acquired taste.  For deep backcountry where weight/distance are issues I like to carry ramen noodles.  They are easily prepared in water that is barely warm, so you can get long life from a fuel canister.  If you try beans/rice/other pastas it takes a bit of boiling to get them ready to eat and uses up fuel.  Other than that, lots of bars.  My favorite right now being the Snickers Marathon bars--280 cal with 21 g of protein.