I really like dessert. I see no need to deprive myself of it just because I'm out in the mountains. Here's a time-tested classic that requires almost no prior planning.
Box of brownie mix
Empty the box of brownie mix into a pot or pan and combine with 1 to 2 cups of water. Add water until you have achieved a consistency on the gooey side of fluid. Place the pan on the lowest possible heat (a mean feat on most camp stoves) and stir like mad for about 5 minutes. The result will be a semi-solid but glorious tasting mess that hopefully didn't burn to the bottom.
Go crazy! Try adding peanut butter, cream cheese, nuts, or anything else that sounds good. It will be hard to go wrong. Keep in mind that this recipe uses an entire box of brownie mix, or the equivalent of a whole 9x13 pan of brownies. It's best shared among 3 or 4 hungry individuals. Also, quick clean-up post-enjoyment is a must.