Yes this has been done before (not here), but from what I have found they never made anything I would eat. More than that they always used ingredients that require shopping for freeze dried goods (expensive) or time consuming using a dehydrator with possibly dangerous results. Scouring the supermarket reading some labels and some experimentation can save you serious money when shopping for backpacking food.
I have been doing this for over 5 years once I discovered you could "cook" in a freezer bag (more like re-constitute and heat up).
The bags / cozys you see in the photos are about 5 years old an instructable will follow very soon if not already, they are simply a pouch made out of foil backed bubble duct insulation, foil tape and sticky Velcro pads. They are also multipurpose: 1 they can be used to pad your back in your pack, 2 you can use them as a pillow (stuffed and a cloth wrap), 3. Cold spot cover for low spots on your sleeping pad.
The photos you see are of scouts in my troop prepping a backpacking meal for 12 (two pouches used). The meal is Chicken with gravy mashed potatoes and stuffing. Not bad after a day of hiking, I have also done other chicken dishes using rice taco seasoning, powdered black beans (Finest Foods), also a beef version.
This has two phases preparation and cooking. I am a firm believer in preparation that way you do not carry in or out packaging. Secondly, there are no surprises at prep time, miles into the woods there are no stores.
Freezer Bags (quart and gallon)
Measuring cups (in this case a graduated 1 cup measure will do)
Cooking Materials / Equipment
Watch cap gloves to insulate your hands while you handle the freezer bags when hot.
Freezer Bag Cozy (shown here easy enough to make but an instructable to follow)
Scout or GSI mess kit cup (with graduated English measures in my case)
Cooking Pot 2 quarts normally 4 quarts for a large group should be fine
Potable Water (drinkable water you brought or filtered)
Can Opener (in my case you can use foil pouch meat)
Stove (heat is a good thing here)
Optional camping spice rack (round container with 6-8 spices in pie shaped compartments)
Serving 4 Real People multiply or divided for your group
2 Packages of Instant mashed potatoes (the 4 serving type that require no milk some are better than others)
1 Package of Instant Gravy (chicken)
2 12.5 oz cans of White Chicken (you can use the foil pouch to save weight but it is much more expensive)
2 Cups of Stove Top Stuffing mix
Sprinkle of Butter Buds (butter type flavoring dried, comes in a salt shaker type container)
DO NOT ADD ANY WATER TO ANYTHING AT THIS TIME.
DO NOT OPEN THE CHICKEN LEAVE IT AS IS. It is only here for Inventory
Take 2 gallon freezer bags place the contents one mashed potatoes package in each, take the air out seal and write mashed potatoes (it looks like the gravy I realize the volumes are way different but there may be an inexperienced scout / teenager handling it) 2 cups water.
In another gallon freezer bag place 2 cups of Stove Top Stuffing, mark this bag with 1.75 cups. The box calls for 2 cups but I have found that given we are sealing the bag no steam escapes, 2 cups made it mushy 1.75 should make is more stiff.
Take the contents of the gravy packet and place it in another gallon freezer bag, mark it with 1 cup water (we marked the potatoes therefore you don't need it here but do so if you want).
Make sure the cans are well separated from the rest of the materials the edges may ding the bags and cause leakage later.
Pack up at least 1 extra freezer bag just in case one springs a leak (there is another reason I will tell you in the cooking phase).